After spending some time with google, this seems like a perennial problem. Does anybody have some (suitably licenced) code to do this? (Not an issue if it is not 100% ready.)
As I really need it, I might end up implementing it myself. In that case, would there be an interest in accepting such patches to Cycles? (Most probably it would be based on the Autodesk SDK.)
We would not accept patches for and maintain FBX support in Cycles, I don’t think it’s close enough to the core of what we are trying to do for us to invest time in it.
Right, those file formats also are not something we would support directly in Cycles. USD and Alembic support we will likely add to the Cycles repository at some point, they are under development.