Memory safety by default in kernel sounds like a good idea :). However I don't think that C is being _replaced_ by Rust code, it's rather that more independent parts that don't need to deeply integrate with the existing C constructs can be written in a memory safe language, and IMO that's a fine tradeoff

Definitely not. Rust gives you a tangible benefit in terms of correctness. It's such a valuable benefit that it outweighs the burden of incorporating a new language in the kernel, with all that comes with it.

Zig offers no such thing. It would be a like-for-like replacement of an unsafe old language with an unsafe new one. May even be a better language, but that's not enough reason to overcome the burden.

And “if you enjoy C++/if you enjoy C” are gross oversimplifications.