I think that right now, there is sufficient motivation to implement enough of this to be able to try it out, and then see how it actually behaves in practice.

But Rust works on a really wide range of kinds of processors - CPUs, GPUs, FPGAs - and hardware architectures (dozen CPU architectures, dozen GPU architectures, etc.), and nobody has shown that this is a net win for all of them.

Figuring out for which, if any, this is a net win, is something that will have to be demonstrated.