Couple of new ideas after watching the stream... if they go with the templates functionality, some of this could be done by modders:

1) Copy map

Sometimes, I want a city/region/world to change climate, be devastated by war, or a volcano to erupt. There may be ways to do this already, I'm not sure. But it would be great to copy a whole map over in order to maintain the same basic shape/structure and change the environment, or replace some models, etc.

2) On the Fly water levels

This could be a templated script from modders, probably. Something to change the water levels in a region on the fly (simulate flooding, etc).