Introduction
The only requirement for vault to be compatible with any HSM firmware is that it needs to support the PKCS#11 library. The requirements are highlighted here
Scenario
When the version on the HSM firmware is upgraded from abc to xyz
Recommendation
When the version on HSM which vault uses needs to be upgraded; make sure the HSM vendor does not require an update of the PKCS11 library to which vault is making the calls.
Also, it is highly recommended to test this version change with a lower environment in vault