@JibbSmart: I'm working quite a lot with linux, even right now that I'm writing this post. In my company there are many professionals working with linux but no one who ever said: "Oh if there was a Portal 2 on linux...". I even got some of them as steam friends meaning even the hardcore administrators tend to use Windows for gaming.

@Rondidon: Too late? Market too small? Think about AaaaAAAAaaaa on consoles! That would be nice. Have you ever heard anything about the Editor of this horror game amnesia? It supports Linux development but where are the games? Why don't studios say "Wow what an opportunity, we are developing for linux!!"... Because it is a too small market. Just my oppinion...