So call me crazy, but I'm taking a quick glance at the sales numbers here and it seems to me that PC gaming never really died but rather the market never really grew to COD type numbers.
The fallacy in that entire mindset is that it presumes "console gaming" grew to COD type numbers. On the contrary, Call of Duty grew to Call of Duty type numbers. Practically nothing else comes close, on any platform.
It's also why people are so radically misinformed about what concurrent player numbers should be deemed impressive. Call of Duty regularly has millions playing concurrently, so when people saw Skyrim doing around 300,000 on Steam, they went "meh".
Again, on the contrary, while Call of Duty does 1-2+ million concurrent players, practically nothing else comes anywhere close.