Same boat here, although I still play WoW. I'm totally bored with WoW except for raiding, because I love the social aspect of it. I can't get into new games because they seem so boring and lonely compared to an MMO. For example, I loved the graphics in Oblivion but I just couldn't get into it because it felt like playing WoW with no other players around. I feel like, what is the point of grinding for gear and levels in a single player game? I really want to still play PC games and be into them like in the 2nd golden-age of PC games (2001-2004), but nothing lately can hold my interest.
On the weekends when my guild isn't raiding, lately I've been extremely bored. I have like 3 new games around and countless older classic games, but every time I try to start playing them I just get bored and stop after an hour. I want to play NWN2, but I want to play it all the way through, and I only have the weekends to play it (because I play WoW on weekdays). Shooters are just totally out of the question any more except for CS on occasion.
I'm not sure if it is WoW that has ruined all other games for me, if it's just that I'm getting older, or if it really is that the PC gaming industry is dying. I don't think it's just WoW though, because I used to play Ultima Online back in the day and that game did not ruin other great single player games of the early 2000's (Jedi Knight 2 & Academy, Civ 3, etc).
I think the problem is that shooters have entirely lost their charm now, new fancy graphics just doesn't cut it any more. Half Life 2 was fun because of the physics and the story, but the two expansions were very tedious to play through and I didn't enjoy them. Portal was neat, but I doubt whether a full length sequel would hold my interest. The last great RTS that I played was RoN I think, no other RTS has come close to the polish and balance. SoaSE was fun for a day or two, but the extremely dumb AI and unplayably-buggy multiplayer has ended my time with it, for now. Likewise, Civ4 was the last great TBS, and while I can get sucked into it for hours at a time, you can only play it so much. I think NWN2 will be fun once I can get into it, although the interface is annoyingly clunky and hard to work with.
I miss the days of the simple, straight-forward and polished games of yore. MoM, MOO, X-Com, etc. I think that's what made Portal so popular, it was simple, challenging, fun, and new. Spore has potential, although I suspect I'll get bored with it after a few days. Starcraft 2 will probably have a good single player campaign worth going through, but I bet the multiplayer will be so uber-competitive that it will be just as frustrating and unfun as WC3.
So, what genres have hope of being fun and new in the future? Perhaps a perpetual MMO-RTS, or some sort of hybrid RTS/FPS. Mass Effect might be worth a go. Blah.