2: I'm pretty sure PC gaming has been growing both in gross numbers and market share metrics since the end of 2011/beginning of 2012. (interestingly enough, that coincides with the release of Skyrim, which was noted for introducing a ton of people to the idea of PC modding and flexibility). So I don't think anyone is 'leaving' PC gaming at the moment. If you had said that in 2010, I'd agree.
I remember one of the old, old criticisms was, "I just bought a $2,000 top-of-the-line computer and it can't even play a newly released game. Forget this I'm just going to get a [PS, Xbox, whatever]."
That's just what I thought of when I saw those charts.
Not everyone is going to upgrade to Windows 10, etc., especially some of your less computer literate folks. Some of these game devs just make me queasy.