So many Garlean characters have been introduced over the years that there's actually a good number just sitting around waiting to be used again. We could have had Nerva reluctantly approach the player character for aid and work to rally surviving Garleans to his side in order to help pick up the pieces and commit to reconstruction efforts.

The Ironworks would probably support such an effort now that the war is over. The crew of the Prima Vista could be reintroduced and would probably support such an effort. Jullus is right there twiddling his thumbs in the frozen train station and would almost certainly support such an effort...and then there's Gaius who could easily have deduced that maybe he can help nudge things back in his homeland in a better direction.

Who knows? Maybe that is what the general trajectory of a hypothetical reconstruction effort will involve but...it'd be really weird if 'yeah, some Garleans went to the moon but everyone else just stayed in the ruined city' is meant to be the conclusion to their story.