BU vs CORE should have ZERO effect on any existing antminer - it's still the same SHA256 protocal that the miner is processing.
I'm also 100% certain that the S9/T9/R4 at least have already updated the controller software to support BU *IF* it actually DID require such a change, since AntPool has decided to support BU.
not that this thread is a possible future , but with BMMiner , one could certainly make a preference set / blacklist. Bitmain won't do that though, they may have taken a position, but they won't forgo profit