A common complaint against Linux game development is that it lacks a standarized platform and different distributions have their quirks. While I don't like Steam and don't use it (DRM, no resale, obnoxious pop-ups...) this is going to give game devs/publishers something to target. In my opinion it will be more psychological than practical. Source engine games, one or unrelated two AAA show up - and suddenly minor devs are starting to think "Why not ? Me too !".

I don't delude myself, though: several dozen percent games still won't show up on Linux. But it beats having to rely on the 5% games that are multiplatform.