There's plenty of independent interest in properly bounding stack usage because this would open up new use cases in deep embedded and Rust-on-the-GPU. Basically, if you statically exclude unbounded stack use, you don't even need memory protection to implement guard pages (or similar) for your call stack usage, which Rust now requires. But this probably requires work on the LLVM side, not just on Rust itself.

Failable memory allocations are already needed for Rust-on-Linux, so that also has independent interest.