My understanding is that tmux is primarily an OpenBSD project, and rust isn't a good fit for them (for reasons that summarize to portability problems), so it is extremely unlikely. Also, this is a hobby project that currently is all unsafe, so there's not even any particular point. (EDIT: Of course, as it gets rewritten the latter point is likely to diminish)
> This project is still early in its developement. Bugs, crashes and miscompilations are expected. DO NOT USE IT FOR ANYTHING SERIOUS.
> rustc_codegen_clr is only tested on Linux x86_64, with the CoreCLR runtime (more commonly known as simply the .NET runtime), on .NET 8. It should work on other platforms, but it is not guaranteed.
I guess it could eventually be an option, but today it looks more like a neat tech demo.