If it were some other open source project I could see where you're coming from, but if there's one community I do not expect to kowtow to language hype and zeal

If it were some other open source project I could see where you're coming from, but if there's one community I do not expect to kowtow to language hype and zealotry it's the kernel devs. You know, the people who still coordinate their development through mailing lists and sending unified diffs around. I write a lot of C, some of it in the kernel (although I don't think any of my code made it upstream since I mostly do vendor code for vendors who don't care for mainlining, so I don't think I qualify as a true kernel dev). Out of the languages you mention I think only Zig could be a serious contender but it's probably way too novel and niche to be a serious contender at this point. D has a GC and is probably less popular than Rust nowadays, Ada uses garbage collection (or other forms of memory management that don't seem very suitable for kernel work AFAIK). But most importantly there seem to be people willing to actually write Rust code in the kernel and add support for it, whereas I don't see a very strong initiative to push Ada upstream...