The problem for Linux games by Id has been the distribution. How do I buy this Quake 4/Wars that Id has ported to linux? Certainly not from Ubuntu software center. Do they have distribution system or do I have to download some binary and house it in my /home/? I don't know and couldn't find out with 1 minute of googling.

I don't think that Valve will have this problem.

EDIT: Quake Live works really well but there is a lot of free competition with Q3 type games on linux.