Consensus is preferred, but it is already clear that certain individuals are unwilling to compromise no matter what, so ultimately it will
never be reached between the whole bitcoin community. Ultimately, 95% consensus will be reached to make this happen. How quickly will the remaining 5% upgrade when the hardfork initiates will also be interesting to watch. My guess is at least 1% will fail to upgrade due to be stubborn or oblivious.

It would be wise for those being left behind to start getting ready to release their own hard fork to solve some serious concerns when they control less than 5% hashing power overnight on a forked coin. They should create their own github and start marketing it to users and miners to solve this serious problem which will make their currency unusable overnight unless they adjust difficulty retarget manually and possibly implement more checkpoints.

It will be interesting to see if their coin survives and for how long? Most miners and pools would be unlikely to attack their coin but with such a small hash rate one group may attempt a 51% attack out of spite, curiosity, or for profit.

Bitcoin has always remained interesting to say the least.