I beg to differ. With gaming becoming more and more mainstream we've reached a critical point where mainstream games have turned into such generic appeal-to-everybody-and-their-lolcat that it leaves hardcore gamers seriously wanting.
Multiplayer (and more specifically *competitive* multiplayer) has become such a required tickbox for publishers that it very often comes at the detriment of the single player experience. While I'm sure most of us enjoy playing games with other people there are just so many genres where single player is crucial and/or competitive multiplayer doesn't make sense (like story driven RPGs). Many of these genres have been watered down to such an extent by now that they're barely recognisable, others have just pretty much died out entirely in mainstream publishers' catalogues (like adventures, not the "action adventure" kind).
The second problem is the "consolification" of everything, some genres are just not fit for controllers (sure you can attach a kb/mouse to a console, but if you do that you just have an underpowerd PC with horrendous limitations anyway) forcing them in a format that "works" for console controllers just turns them into something they aren't and that people often just do not want ("Hi Dragon Age 2!")
Thirdly are the horrendous limitations consoles impose, sure the mainstream gamer might not care too much, well, until he/she sees how you can mod some games (like Skyrim...) often fixing bugs the developers can't be bothered with, fixing broken game mechanics and just generally improving the game experience. The gaming PC isn't dead yet even though publishers might be trying very hard to kill modability in the mistaken belief that mods kill DLC sales (well, they will, if your DLCs are trivial drivel).
This explains imo the huge success of crowsourcing for games lately and frankly I think there is a market for both groups, the big publishers can keep on cranking out Hollywoodstyle appeal-to-all games while the crowdsourced developers can keep on producing interesting, innovative, oldschool or just generally off-the-beaten-path games. It's happened with film, I don't see why it would be a problem with games.
tl;dr Single player is not dead and PC gaming is far from dead either.