A safe ABI would be cool, for sure, but in the market (specifically addressing your prediction) I don't know if it's really that big a priority for adoption. The market is obviously fine with an unsafe ABI, seeing how C/C++ is already dominant. Rust with an unsafe ABI might then not be as big an improvement as we would like, but it's still an improvement, and I feel like you're underestimating the benefits of safe Rust code as an application-level frontline of security, even linked to unsafe C code.