This vid is a good explainer of your question. To me as a BIP110 supporter a hard fork PoW change is a non-starter. At the same time if BIP-110 fails I firmly believe Bitcoin as we know it is over and it’s probably not coming back. You can’t have perfect money if your blocks are 40% non-monetary junk that competes with the monetary usecase. Bitcoin then becomes like silver is to gold and it will be demonetised in not too long.