And really, Gendry and Arya? Baratheons (not that he's really one) and Starks are poison to each other – remember the dire wolf bitch killed by a stag at the very beginning of AGOT? Arya is considered to be most like Lyanna; Lyanna didn't want Robert. Sansa was supposed to marry a "Baratheon" and look how that turned out. Robert basically killed The Ned by failing to give him the support he needed.
I see so many people saying this and I really don't get it. In fact it seems that the Baratheons and Starks have always gotten along. I can't remember but I'm pretty sure there was mention of how they've always been allies.
One romance not working out does not mean the families are poison for each other. Like you said Joffrey is not a Baratheon, he's a Lannister. And the direwolf in the beginning is foretelling Ned's death (and likely Robert's too as the stag probably didn't get far before he died too) but I don't think it was really saying 'Baratheons kill Starks!'
IMO, the great unrequited Stark love story was between Ned and Ashara Dayne, so if a Ned look-alike and an Ashara look-alike should get together, that would be a very happy closing of the circle IMO. On the other hand I don't believe Arya will have a conventional relationship once she sets her mind on such things. What is she now, 11? Can we not set her future in stone so early?
Of course her future is not set in stone. Nothing is a sure thing in this series! But it's fun to discuss and debate. And if we couldn't discuss the futures for the young characters in this series there would be very little to talk about wouldn't there.