I've not only said it for years, but I've seen it almost everywhere I go (to paraphrase): "If only I could play [my favorite game] on Linux, I'd ditch Windows tomorrow". I've seen it since the mid-2000's (remember all those "The Year of the Linux Desktop?" articles all over the tech blogs before Android showed up? Yeah, maybe next year...), and now it's cold, hard reality. So where are all my switchers?
Still on Windows.
Why? Because when you can play with your phone every 10 minutes and Windows 8 came pre-installed on your new laptop and SteamOS is going to be on the next console you buy, who has time to mess around with switching to a Linux desktop?