I have read that Antpool among others are already on board with BU... and are just waiting a unknown threshold to start mining BU and not BTC.
Umm... BU
is Bitcoin. Merely with a user set max block size. What they are waiting for is a clear indication that a large enough majority supports this concept of emergent consensus. At which point, all but an intransigent 1% will accept the new paradigm and switch to a larger-block-capable client -- be it BU, patched core, or other.