Czar of the universe answer is to fix this in an elegant way early with a decade or so to move the coins before anything consequential happened. In the real world, you would never build consensus for such a thing. Even if you did, the process would be so contentious that a vocal contingent could cause a substantial loss of faith in the immutability of bitcoin. It might even be preferable to let the chaos play out. Unless there's overwhelming consensus, any solution becomes a poisoned chalice - even if it's technically elegant.