Since Valve moved Steam to Linux, especially indie developers put more effort in porting newer games, which I actually want to play.
Considering most indies released past year or so started development several years ago, I doubt Steam had had major effect on porting games to linux YET or are there many Windows games that have been ported after
Steam Linux support? I'd give more credit to humble bundle that has been cross platform from day 1. Other major contributor has been Android and kickstarter phenomenon is also pushing things forward with many games either having linux support from start or as strech goals.
Still, I don't doubt it encourages more linux ports in the future, especially if Steam Box becomes popular after release (It runs linux if I recall correctly). I actually have been wondering for years, close to a decate, why no one has developed a linux distro specifically for gaming.
Windows has the status of a "legacy platform" for me and may be gone by 2020.
Microsoft does it's best to marginalise it's own OS considering how shitty Win8 is. They obviously learned nothing from their blunder with Vista. They did not learn that they can't force major unwanted changes to an OS and expect users to just adabt so even today XP is still second most used OS around. MS devs must be braindead considering they try to force tablet OS into keyboard and mouse driven PC.