For your AAA full-fledged games to work on Linux, it's not just Valve - the Big-iron game engines such as RAGE, CryENGINE, FrostBite 2, etc also need to be port

For your AAA full-fledged games to work on Linux, it's not just Valve - the Big-iron game engines such as RAGE, CryENGINE, FrostBite 2, etc also need to be ported and supported. Only then will AAA game makers be able to support Linux games.