Obviously, CFB didn't make every mechanism it branded. At CFB, the institutional knowledge of working with those movements is there, and there is plenty of room to follow that work. The THA catalog of complications also includes many 1990s and 2000s mechanisms beyond the scope of Rolex's usual catalog. Working with a supplier often is a stepping stone to self-sufficiency. AP didn't design the JLC 920, but it's been built in-house at Audemars for decades. IWC and UN didn't design the 1990s chiming mechanisms, but they became part of the fabric of their constructions. I can't imagine Rolex working with a supplier on a prestige watch, but I can imagine it picking up where the supplier left off.
Best,
Tim