If I had a lot of money…
I’d buy PlayOnLinux and Cedega and Crossover Games (while maintaining a great working relationship with the good folks still at Crossover working on apps) and put together (with some hefty funds behind them) a crack team of DirectX hackers and previous Microsoft DirectX programmers to put together a fully-functional, working DirectX emulator for Mac and Linux. Then, port all those changes back into the Wine trunk while promoting an off-the-shelf Windows games player.
I truly believe that if games worked on Linux flawlessly there would be a greater adoption of Linux on desktops worldwide. I know locally it is a huge hurdle to jump. All of my friends are interested in Linux, two of them have the ISO sitting on their desktop. Why are they not making the switch? One: Games. The other: Sony Vegas. People want to use it but they want their games too!
Game development and publishing companies wouldn’t have to write games to be cross platform if the emulator worked perfectly. They would go on making Windows games while Linux continues to grow in installed user base.
Making games for Linux is not the answer, making Linux work for games is!