I say "risk" because any such OS would probably be available under a license more permissive than the GPL. The result would almost certainly be that large parts of the OS would become proprietary (NVIDIA has already tried this with Linux's limited module support).
Of course, moving to Rust is also a risk in this respect, since the LLVM toolchain is BSD-licensed, but hopefully Rust support will be added to GCC in the not-too-distant future.
Except of course, the GPL is why linux remains so popular. A linux killer cannot be a linux killer unless it is GPL or similar. Or else BSD would have over taken linux a long time ago.
I say "risk" because any such OS would probably be available under a license more permissive than the GPL. The result would almost certainly be that large parts of the OS would become proprietary (NVIDIA has already tried this with Linux's limited module support).
Of course, moving to Rust is also a risk in this respect, since the LLVM toolchain is BSD-licensed, but hopefully Rust support will be added to GCC in the not-too-distant future.