I'm not sure what you mean by decide to fall.
At height 961632 BIP110 nodes start throwing away any block that doesn't signal BIP110.
They either get the heaviest chain and reorg the others, or they create a new shitcoin.
The latter seems far more likely at this stage. But there is a chance miners will make a reckless last minute change and successfully 51% attack the network to activate BIP110.