The father of both open world video games and cinematic storytelling in video games, a game several years ahead of it's time, with an open world, day/night cycle, dynamic weather, and fully voiced NPC's several years before most of these things started showing up in other games. Shenmue was left unfinished 2 games in, leaving fans without a conclusion to the story, hence why so many people want it to return.

I can't really see Valve doing that, it would alienate their huge PC fanbase too much, even if it was a timed exclusive. 

I agree on Fallout, definitely too big, and the insiders themselves have said that it's definitely not something as big as Fallout, Red Dead, Resident Evil, or Mass Effect. As for KOTOR, it's sales are lower than those 4 high-tier games the insiders have mentioned, only a little over 3 million on Xbox and PC combined I think. I think it may just be small enough to possibly get nabbed as an exclusive, especially since Microsoft managed to get Titanfall from EA. 

I think most of the third party "exclusive" stuff is gunna be x1 n PC exclusive. If the rumored game/s is kotor 3, left 4 dead 3, mass effect, splinter cell time splitter, jade empire, fallout(very doubtful maybe dlc for that one) than I think it's also gunna come to PC,