This is true. It is a combination of both HW/FW component. The chip that runs them generally 5- 10 years old. but the firmware is newer.
I think judging from the usecase of auracast that it requires new HW/FW/SW combination that the current chip platform cannot provide.
However I don’t see the issue of adding BTLE Audio without auracast extension to it.
If history repeats, It is like resound/Cochlear adding ASHA protocol to Quattro HA / N7 sound processor in a firmware update back in 2019.