God, I hope not. Ground-up rewrites (when they even succeed) typically lose features, performance, and security, since they don't have the benefit of 20+ years

God, I hope not. Ground-up rewrites (when they even succeed) typically lose features, performance, and security, since they don't have the benefit of 20+ years of correcting mistakes. Plus you lose all your contributors. However, Rust is linker compatible with C, and can be runtimeless, so rewriting the kernel piecemeal over time instead could be great. ;-)