I imagine the project is big enough now that anyone who would undertake it would want to be compensated for it. And since that is unlikely to ever pass the cost/benefit ratio for any given corporation, it's unlikely to happen. Not to mention the potential for alienating of the entire existing kernel development group.

It would be much easier to submit patches to slowly upgrade the kernel to a memory safe language, but that would require a lot of political savvy to push through, also making it an unlikely path to be taken. Ultimately, you'd have to convince Linus of the merits, and we all know how much he likes complex languages.