It's not that simple, you don't just need games to exist for a gaming platform to stay viable, you need good games that people not only want to play, but want to play on that particular platform, and the PC has less and less of that.
What the PC does have going for it at the moment is (MMO)RPG's, RTS'es, and casual/puzzle/made-for-your-mom games, and i guess also Flightsims (but this market has allways been extremely slow, releases are ages apart), in thease markets it still has some strong exclusive franchises that people want to play on their PC.
But all the rest are falling by the wayside, with only very rare exclusive releases, and whilst we still get many of thease titles as ports, that's no real reason to play them on the PC, often the PC version is the worst version (if for nothing else, then the DRM it has to put up with), and you could just as well be playing them on a cheaper Console.
For all thouse of us who want to play shooters, racers and all the other action oriented genres, the PC is in a dire state indeed, because thouse games have all but fully migrated to the Consoles, and all we get a DRM filled ports of them that never live up to the potential they could have as PC games, so it's no wonder that so many people choose to play them on their Consoles instead.
Sure, there will allways be games on the PC because it's an open platform, in theory, anyone could make a game for the PC, there exists plenty of open-source tools for it, and stuff like the MMO's and RTS'es are unlikely to migrate from this platform entirely, but we all know what this means, it's more and more becoming a niche platform.. and as a person who cares mostly about the FPS genre, that is a problem for me.