I just watched the recent desktop tuesdays and really liked the progress you guys are making and the idears you are toying with.
What sparked an idear was the exploration system that will spawn more bioms near you after you used the meguffins.
The natural problem that develops is that you get vast maps and big areas to travel and it would rather make sence to create multipel towns then and maybe little trading posts on the way between them. that would vastly expand the number of hearthlings you would need. But the plus would be that you develop an multi town system that can focus on producing certain things that the new recourses allow. Than bringing it back with cariages or horseback to the main town to develop it more would be fantastic.
But how to handel all these masses of hearthlings and new animations? i think a new approach on what we the players are for the heartlings would make it possibel. Maybe we could become their God and we start out with a small shrine instead of the fire. With that we could argue that if you zoom out a lot that all our heartlings become small spirit orbs that just wonder around and only if we focus on them we see them fully. With that you could input an drawzone for heartlings animations and complexitiy what in other way would open up the world to be more expansive and more complex. And with the god argument it wouldnt break our imersion that we sometimes need to scroll in and go up close to see our heartlings do their busy work.
Its a big streach but maybe this idear could help
Love the game and where you are going with it!