I kinda like the soft fork idea. It's a reversible countermeasure to protecting Satoshi's coins. But not the end of the world if we do nothing. Odds are that the attacker will be some entity that's already really wealthy, if they're one of the first to get their hands on a powerful enough quantum computer. Perhaps some billionaire will steal them and then burn them. One can dream.

Oh, what happens next? Do exchanges allow these coins to be sold for fiat? Do reputable institutions do business with this entity and keep it the DL?