It's already a good gaming platform. What you mean is when will it be an "easy" gaming platform. Give it a year. Where Id lead, others follow.

Think of it this way : gaming is driven by necessity. Once Linux is widely recognised as a better platform than Windoze, and with efforts like Wine making DirectX support and titles like Half-Life a priority, I think in the long term a complete shift to Linux for (PC) gaming is inevitable. Some of the people who I think will be instrumental in this include : Red Hat - they have a brand. Redmond Linux - they have the cajones to appropriate some elements of Doze that favour gaming. Id - they have the product. Activision - they have the licenses and marketing / distribution push. Ericcson (and the other phone manufacturers) - client server tools. (I will explain this in more depth in another node!) (OK, speculation time:) Sun - I think that putting Java into all the places that Linux can't oust from Windows (ease of product installation, GUI) would at least make the end user's life easier. Platform agnosticism is a better cause than platform zealotry. Mainly, gamers themselves and therefore game developers need to be attracted to the platform.

The whole Open Source side of things is a different argument entirely. We have started to see a few games getting put under the GPL after they've sold well enough. But basically, games are an entertainment product. They are the only pieces of software (other than really high-end apps) that I can see people paying for a decade from now. They already offer much more than what's in the box through multiplayer and extensibility. Basically, although Open Source is nice for essential things, games are ART - there is intellectual property, a focussed vision, and highly tuned design going into a game. Would Star Wars be as good if Lucas had sent the script out to every sci-fi buff in America with a cine camera? (controversial).

If game engines start to converge however, then they should be as open as possible.

Update : If games for Linux can be made as easy to install as Helix Gnome Desktop is, then it should be fairly trivial to port more games to Linux, and sell a few too. Also, either cloning DirectX or encouraging people to use OpenGL would help.