If there happens to be a majority NO to any kind of freezing or mandatory migration, I would not consider any compromise at all with those that propose these things. Let them fork themselves away to their own "Bitcoin Quantum Safe", they take the the BQS ticker. 
I don't think anyone is crazy enough to propose another hard fork and I hope it won't come to that. A split like that can hurt both camps if you get plenty of proponents on either side. A hard fork should be the last option after everything else have been tried. The enemies of Bitcoin would rejoice and support any weakening of the system.