Yes, I love your idea of an upgrade. When you have the screen in map version, it looks like there is more to the island. Maybe the upgrade could divide your villagers into groups and they could move to other areas and improve them, populate them, whatever. Then instead of having to start 5 different villages like we're all doing now, we could just move from one new settlement to another, checking on the villagers we all know and love!

They could even have special events, like harvest time, where villagers would come from all over the island to help each other harvest, or a yearly celebration of their arrival on the island, oh the possibilities!