I feel there are three possible outcomes that could have occurred if the Ancients were allowed to go ahead with their Zodiark plan and Venat (and those who shared her view) chooses to just sit back and watch.
  1. The planet goes on as normal until everything else in the universe is dead.
  2. The planet goes on as normal once all the new races are sacrificed and the Ancients revived... but then what? Those who were enthralled no longer have a purpose. There's a possibility that those tempered by Zodiark will "retire," now that their purpose is done. If Zodiark's Primal influence is just by proximity, then the people can live on just fine (but Elidibus will forever be alone). But if its on a global scale... now nothing could happen, but those tempered by Primals tend to only have one goal/purpose and I doubt Zodiark really needs any help keeping the Final Song at bay.
  3. Themis is killed in Pandaemonium (no WoL to travel back in time) and whatever is in there that's capable of corrupting the Ancients is able to leave unabated.

Anyway, that all has nothing to do with localisation. I'm personally fine with how the localisation is.