Older game compatibility might not be so much of an issue in itself. You have the same thing with Windows to a degree, plenty of DOS / Win95 era titles are not

Older game compatibility might not be so much of an issue in itself. You have the same thing with Windows to a degree, plenty of DOS / Win95 era titles are not directly compatible with newer versions. Same with older consoles. What tends to happen is either there is a re-release to cash in on a previously successful game or compatibility tools (WINE/DOSBOX) become good enough over time. The biggest hurdle is the lack of a killer reason to run a Linux gaming system over a Windows system or a console. AFAIK there is no big title in the works that will be in any way a Linux exclusive. Here the open nature of Linux actually works against it to a degree, since the underlying stack is open source, dependencies can be (and are) ported to other platforms with less technical and legal issues then proprietary systems like DirectX.