BU just as segwit will always keep sufficient minority share to oppose changes.  That's how bitcoin was designed.  BU was never going to happen, the reason for BU to exist is to oppose Segwit ; the reason of segwit to exist is to oppose BU.  This is just part of the antagonism that keeps bitcoin immutable.

Bitcoin will be a decentralized system, based upon 3 non-colluding oligarchies: the miners, the devs, and the whales.

The normal bitcoin user is the greater fool that finances these three antagonists, that will never be able to come to any other agreement (consensus) than grossly the original protocol that is running now.  So no bigger blocks, no segwit, no change in PoW, nothing ; simply because any of these changes would put so much gain in the hands of some, and inflict so much losses on the heads of others, that they will resort to "politics" to stop the change.  

The day that the devs are the biggest whales and are the miners, bitcoin will be the centralized bank it will, eventually, become.
At what power level, I don't know.

Bitcoin's immutability is similar to the reason why we didn't get a nuclear war in the second part of the 20th century: the MAD doctrine.