I have no doubt that such a scenario is plausible, I just don't know if it would be a good thing if the mainstream becomes Linux "aware". It seems like everytime something good comes along in the tech industry, somebody else that has stockholders to satisfy comes along...markets it to the mainstream (re: as many people as possible)...and completely ruins whatever it is that made it great...usually by dumbing it down and restricting it somehow. Valve isn't publicly traded, but if they find success, who else will follow their path?
I don't know, maybe it would be a good thing. I am just skeptical.