12million WoW players on a total of 100+milllion more or less assiduous PC gamers is a very good result, but doesn't speak for the majority of this platform players.
PC gaming always had ups and downs, but the platform won't die easily, it has amongst its weapons a very large user base (although hardcore PC gamers are a minority, but still some tens of millions strong), a huge SW legacy and a continuity more than a decade long (just as DOS had).
Edit: ^^ just counting W9x/NT platform