>as the platform under it (the hardware, the kernel, etc.) changes to the point that it becomes non-functional. The kernel has a pretty strong backwards-compat

>as the platform under it (the hardware, the kernel, etc.) changes to the point that it becomes non-functional. The kernel has a pretty strong backwards-compatibility stance, so you'd need to wait a long time. Nobody stops you from running an outdated and insecure distribution to use X11 (in this hypothetical future). Nobody stops you from patching X11 to support newer interfaces. If you want to stick with X11, you can. Nobody urges you to upgrade.