Linux has made huge, huge, strides in gaming. The platform itself isn't the problem, there are thousands of games on Linux and I no longer have a Windows partition for gaming.
The only blockers at the moment are companies like EA, Activision and Ubisoft not releasing a Linux version of their games. They will say it's because of a lack of marketshare (which is fair enough) but it creates a chicken-and-egg situation where a large percentage people won't move because FIFA and COD aren't available, and they're not available because the big userbase isn't there.
I have more than a lifetimes worth of good/great/exceptional games on Linux so as long as you don't expect everything (and having a console to fill in the gaps can help) its perfectly viable for gaming, depending on the games you like to play.