When all 3 end portals have failed to spawn there is no way to get to the end

When all 3 end portals have failed generating, either because ravines have been generated instead where the portal rooms should be or because the chunks the strongholds are supposed to be in were generated before the portal was implemented, there is non way to get to the end in legit survival. I don't think this should require starting a new world and lose years of progress. perhaps there could be more than 3 chances to generate strongholds?