Basicly for those that played the last game, the end result will be that Sanix divulged info that allowed them to find a secret weapon to defeat Alcarin and Seygora. They turned the imbalance in onto Alcarin and Seygora's world and it was destroyed instead. After the dust settled, the portals were gone.
However, the technology to cross worlds with an airship remained, and was used. Now there has been trade, alliances, and peace struck between the different worlds, and airships bus people from one city to another fairly regularly. We would make a number of minor villains rather than one big plot, and sort of just flow. When you choose a character, you start by telling what the fate of their parents were, if they're alive, retired, or deceased so on.
People who would have especially long life, might still be alive, I'd have to deal with that on a case by case basis.
This is highly preliminary. Thoughts?