Regarding the Littlefinger/Reyne theory, I really want it to happen. Numbers said it doesn't have a proper build up, but then again, Rains of Castamere is shoved down our throats almost every alternate week thanks to the show and it is also incorporated in the House Lannister theme.For it to figure into the backstory of one of the game's biggest players who has been systematically and carefully breaking down the Lannisters from the beginning of the series would just be thematically beautiful. I also find the Alayne/Ellyn+Rohanne thing to be interesting.
Just think. If Baelish is indeed the last surviving heir of the Houses Reyne and Tarbeck, then if the Lannisters are completely decimated (which seems to be his endgame), then he can claim the Westerlands for himself once he has regained Reyne/Tarbeck's lost status. He already has the "Key to the North", who could also be the key to the Riverlands if Edmure Tully dies and his issue with Roslyn Frey perishes. And he already controls the Vale.
So basically he will own everything worth owning north and west of King's Landing! And once the Lannisters are gone, he could claim KL, the Crownlands AND the Iron Throne for himself! Or through Sansa. And all without anyone, not even Varys, seeing it coming. Epic game is epic!