Functionally, Bitcode delivers – a .bc file can be compiled into any architecture LLVM supports. I have tested a few supported architecture, and it worked like a charm.

Stability of the Bitcode format across releases is orthogonal to the functionality it provides. Given that OS/400's TIMI has been a long-running success, it is possible to put extra effort into stabilising the Bitcode format as well. Benefits would be numerous and significant, ranging from CI/CD to apps taking advantage of new or enhanced ISA extensions.