I'm torn on the subject of a binary-stable driver interface. The idealist in me likes that it forces vendors to open source their driver code, but the pragmatist in me knows that some vendors (like a certain graphics card manufacturer in the desktop and server world) probably never will open source their drivers, and if they do, they may not be as high of quality as the proprietary version for other OSes. I wonder if there is some middle ground. Also, even with open source drivers, the lack of stability has downsides, such as requiring you to recompile all drivers whenever the kernel updates. Maybe where a subset of the ABI is stable, so it's possible to build driver binaries that work across kernel versions, but there is still some incentive for keeping drivers open source?

> any improvement that could be added to Fuschia could be added to Linux

This is not necessarily true. Some things certainly. But linux is constrained by keeping a backwards compatible user-space interface, and being mostly posix-compliant. For example, fuchsia doesn't have fork or exec (it has a single spawn function/syscall instead). Linux could add a new spawn syscall, but has to keep fork, clone, execv, etc. forever. And even if most new code moves to use the new syscall, the complexity around the old ones will be around forever.