From Kotaku:
It's ridiculous and foolish to say that PC gaming [is in decline]. I've seen some of the dumbest quotes out there about the business [falling apart]. It's just not true. The simple truth is the online business is picking up in a huge way. If you're able to add in - and NPD is beginning to track this stuff - the digital sales and regular sales and subscription money and all that stuff, the PC gaming industry is at its strongest point in its history period.
So what he tells us is true...from...a certain point of view. Though I'd like to see the numbers that have it at its "strongest point in its history" if you took WoW out of the equation.
Even studios owned by console manufacturers believe that PC gaming is doing just fine.