From Valkyrja
I love Sansa and Sandor's connection and think it would be great if they could find a way to be together (married?) at some point, though I am not sold that a marriage between them will actually happen. I agree that it is not a political impossibility though. It *is* significant (and heartening) that we have seen some types of female-choice relationships (like Asha/Qarl, Alys/the Thenn dude, etc.) and I do think that this will tie into Sansa's storyline, which I hope will include further resistance to full submission to a patriarch-arranged marriage. Yes, she may play her part in LF's schemes, but I obviously hope that she subverts said plans at the same time (I have no clue how that will play out). I think that her thoughts about being wanted only for her claim show more than simple sad acceptance of this fact...or at least, I hope it signifies more. Because I don't think I want to read an entire storyline that consists of Sansa doing LF's every bidding and becoming completely twisted by him. I don't mind her 'appearing' to do this, as long as she is coming to a point where she is also trying to resist, mainly because what LF wants for her is not what she wants. Also, LF uses very questionable means to achieve his ends, and while I could handle Sansa 'dabbling' in this moral grey area (like Bran and Arya are doing in their training), I think it would be very difficult for me to see Sansa (or Bran and Arya, for that matter) fully embrace the 'dark side'...that is, of course the Dark Grey Side, lol.
That said, I can and do see Sandor coming back into Sansa's storyline. There has been too much reference to him for this not to happen, imo. I do agree that the Hound's terrible reputation is going to come back to haunt Sandor, but I am really not sure how that is going to play out. Either way, it is possible he may have to 'answer' for those crimes, even the ones he did not commit, perhaps in another trial by combat. He may die in that, or in a fight against Robert Strong, or some other way. Or he may live. I agree with Lyanna Stark in that I think
it would actually be better for Sandor to live (for all his sins, he has suffered greatly already) though I am still unconvinced that he will survive the series, mainly just because I am trying not to get my hopes up too much, GRRM has dashed my hopes too many times.
But putting aside the whole thing about Sandor/Gravedigger answering for the Hound's reputation for a moment, let's say he enters Sansa's storyline again: what kind of role will he play in relationship to her? And for how long? Again, I don't know, but I can't help but go back to the text to look for possible symbolism and foreshadowing. There are some mixed messages depending on how you interpret said symbolism, but it is definitely there.
First, as early as AGoT, you have the whole 'get her a dog, she'll be happier for it' throwaway remark by Robert, which some take to mean that Sandor is a type of replacement for Lady. Then you have Sandor's own "A hound will die for you, but never lie to you", which could be seen as foreshadowing that Sandor *will* become Sansa's 'dog', but that he will subsequently die for her. However, it could also be read less literally, because, as the SSM quote remind us, the Hound persona already *has* died. Perhaps, in his mind, Sandor has let the Hound part of him die in part because he feels he failed Sansa? (See: his last words to Arya.)
Of course, as Brashcandy has noted above, we also have the "I'll have a song from you", and the symbolism of the white cloak, the (un)kiss, and the blood (which Sansa is still thinking on even in AFFC). Sandor gives Sansa his cloak twice while they are at KL together, perhaps third time is the charm.

And we all know that cloaks = marriage, or at the very least, protection in Westeros. Yes, the cloak means something else for Sandor as well, about the hypocrisy of the ideals of knighthood and especially the hypocrisy of the kingsguard. Also, with the blood, we have Sandor who is actually physically present when Sansa 'flowers' with her first moonblood (and no, I'm not talking about the creepy scene in the tv series, see rather: ACoK scene between them on the roof before the battle -- the second time he stops her from falling from a great height, it is because she felt sick due to her period starting), and the blood that stains the cloak on the night of the Blackwater, the blood on Sandor's face as she cups his cheek. Later, she associates him with the kiss (however much that is made up,and for good or ill, for Sansa he is associated with that significant moment). She later seems to take pride that she has kissed a man (and the Hound of all people) whereas the Tyrell girls are still giggling about kissing boys. Again, these are significant moments when Sansa is starting to 'become a women' at which Sandor is present.....perhaps there will be a 'third' time here as well.

(So to answer the question, yes, I think there are signs pointing to him taking her maidenhead, though I am still ambigous about an outright marriage. More on that later....)
Regarding Sansa remaining Alayne Stone: I too am torn about this possibility. I've always thought that she was just on a long journey like Bran and Arya, and that part of this journey required her to shift her indentity for a time under a different name (just like Arya's facechanging and taking of different names), but that eventually she would reclaim her 'true' identity. However, upon thinking about it further, I am no longer certain the outcome will be so clear-cut. The theme of identity is most obviously exemplified by Theon/Reek's arc in ADwD, 'you have to remember your name'. Theon does remember his name, but it is not like simply remembering his name makes him whole again, or makes him the person that he was before. He is still incredibly damaged, and had to be forced intitially by Roose Bolton to reclaim his identity. Twistedly, Theon even keeps encouraging poor Jeyne Poole to pretend to be Arya....to 'remember her name'.

I think the point here is that if you go long enough under a different name and identity, the line between which is your true name and which is your fake name is blurred. I still think that at least some of the Starks will return by the end of the series, so someone at least needs to remember their name. Whether Sansa will or not, I cannot say yet.
So, are there any signs pointing to Sansa remaining Alayne Stone (other than the So Spake Martin quote)? I could be going crazy, but I think I remember somewhere that in the tv series, they've made a conscious decision regarding Sansa's wardrobe (I think they said it was a 'hint'?) to have her dresses decorated with dragonflies (she also wears a dragonfly necklace iirc). What the heck would dragonflies have to do with Sansa's storyline??? I thought to myself. At first, I thought perhaps it was a hint that Sansa would becoming involved with/married to a Targaryen. But then I remembered......dragonflies are *not* dragons.....
I was re-reading the Dunk and Egg stories, and the imagery of the dragonfly is one that comes up throughout
The Hedge Knight. In the beginning of the story, Dunk sits under his elm tree musing that a dragonfly is nothing like a dragon. Then, at the end when Dunk is speaking to Prince Maekar regarding whether or not he should come live in Summerhall with Egg, or instead take Egg on the road with him, to live roughly amongst lower ranking landed knights, hedge knights, and smallfolk:
Quote
What shall it be, Dunk? he asked himself
Dragonflies or dragons?
Dunk feels strongly that it would be good for Egg to live amongst the people, in disguise, and flat out tells Maekar that it will be in Egg's best interest to do so (look what happen with Aerion who was so pampered as prince of the realm, he notes):
Quote
Maekar Targaryen, Prince of Summerhall, reguarded Dunk of Fleabottom for a long time, his jaw working beneath his silvery beard. Finally he turned and walked away, never speaking a word. Dunk heard him riding off with his men. When they were gone, there was no sound but the faint thrum of the dragonfly's wings as it skimmed across the water.
So, here we have dragonflies vs. dragons seeming to represent a choice between two paths: that of highborn life, and that of lowerborn life.
But it seems to mean more than that as well, as seen in regards to what we know about Ser Duncan the Small, known as the Prince of Dragonflies. From the wiki:
Quote
Prince Duncan fell in love with a woman known as
Jenny of Oldstones and
loved her so much he gave up his crown for her and married her against his father's wishes. It was possible that after this he became known as the
Prince of Dragonflies.
So here we have the dragonfly imagery being taken further, to show that Egg's own son later decided to reject the crown because of his love for Jenny of Oldstones.
I would not even have brought this up if I didn't remember the thing about tv!Sansa's wardrobe supposedly being some sort of meaning. I could be totally reaching here, but I think it could be taken to signify that Sansa might do something similar in the future.
From ASoIaF text itself, we know that Sansa loves the story of Queen Naerys and Aemon the Dragonknight (which is a story of forbidden love) at the beginning of the series, but I'm not sure how she thinks of it at present. The reality behind that song was quite dark, imo, with Naerys quite a sad, mistreated figure, whom Aemon loved but did not seem able to fully protect. Not sure if it represents Sansa's situation at KL, or if it represents more generally how naive Sansa was in having that song as her favourite, due to not really understanding the true story behind the song.
Edited to say: Sorry again for how long this is, I've been trying to catch up on this fast-moving thread and more people kept posting before I was done with this....so I apologize for how disjointed it is.