That threat definitely kicked this whole thing off. With Windows 8, Microsoft made moves for a Windows App store only version of Windows. It didn't pan out for them, but had it it would have effectively killed Valve at the time.

I think Windows 12 will likely renew that push. Valve has positioned themselves to resist it, and in Microsoft does do a strong push in that direction, it is possible they will lose the PC gaming market, in large part thanks to Valve's work.

Many are resistant to trust a corporation, and I agree, but Valve isn't a normal corporation of that size. They are owned by one guy, and as such his choices are the only ones that matter. As long as he keeps making the right choices and Valve doesn't go public or sell out, they will likely continue being a good shepherd of PC and Linux gaming.