Gentle Observer checking in to make a comment. I posted this on Heresy as well, but figured I'd drop it in here for discussion.
I've been operating on a broad general assumption that GRRM is basically rolling back "the wheel" of Westeros' history by replaying/reimagining the great wars and conquests throughout the kingdom - each conflict we see in present day is a reworked version of a previous one. For example, AGOT opens with a Stark/Lannister enmity that leads to the Wot5K, which could be seen as an Andal/First Men conflict. Dany is positioning herself to be Aegon the Conqueror 2.0, and there's a good chance that Jon will become the new King in the North (that I speculate will eventually face off against a dragonlord conqueror, but this time no Stark will bend the knee - that's another discussion, however). WE might not get ALL of the redux battles and they might not happen in exact reverse order, but I think we're close.
With regard to Euron, recall that Aegon I came to Westeros and roasted Harren the Black - Harren Hoare, cruel, evil, bloodthirsty despot and ruler of the Iron Islands. Black Harren built his castle with blood and sorcery thinking that he will be the king to end all kings, and Aegon hails up with his big black dragon and puts an end to that tout suite. Aegon gives the Riverlands to House Tully as thanks for their support, and bequeaths the Iron Islands to House Greyjoy.
Now we see Euron Greyjoy show up as this cruel, evil, bloodthirsty despot that now rules the Iron Islands, and across the Narrow Sea a new Targaryen conqueror with a huge black dragon has turned an eye toward Westeros. Euron is wearing this crazy black armor and is building his fleet - and his "castle", the Silence - with blood and sorcery. If the spool of time is being unwound, I will not be surprised to see Aegon Revisited meet up with Euron the Black, self-styled king of the Iron Islands. What will Drogon do to the Silence? Will the Targaryen conqueror take back the "gift" given to House Greyjoy 300 years prior, ending a short reign of terror, or this time will Targaryen side with the Black King in blood and fire? Bonus points if something big and epic goes down at Harrenhal.