I do not know for certain. This is definitely an interesting situation. It is true that the Intel cards pretty much require ReBAR for decent performance, but I have seen multiple references (don’t have time to find them right now) saying that ReBAR is not good over USB4. Not sure if it’s specific to AMD USB4, but I would hazard to guess that most gamers these days are using AMD CPUs.
OCuLink does not have some of the issues associated with USB4 simply because it is a genuine PCIe connection; it doesn’t tunnel PCIe over a USB4 connection. Latency and bandwidth are much better, but you cannot hot plug (you have to shut the machine down to connect/disconnect OCuLink on the FW). Always tradeoffs.
If you are using a FW16 and considering OCuLink, there are multiple threads, and even a custom OCuLink adapter for the dual M.2 expansion bay. Someone is also working on a full custom 8-lane OCuLink adapter for the FW16.