You're right. You'll have no problem playing games in Win8, at all. Moreover MS guys are saying DirectX 11.1 is gonna be a huge improvement and will help a lot to provide better graphics with low drop in FPS.
Gabe Newell is talking about the Windows Store. He believes paid games will rise in price as distributors will be 'forced' to publish their games in Windows Store only. It's just his prediction and it has got nothing to do with how games will run or technical issues. If you don't buy games and use the 'other' method, you can just chill.