IDEAS: How to add new biomes without requiring world restart

First off, love this game!  Keep up the great work!!

I do love that recent updates have added more base attack events, and that more enemies appear in those attacks, and at night.  Those changes have made the combat more enjoyable for me.  

However for many of us who have enjoyed the early release, we have beaten the major bosses already.  Since that’s the case there is not much to keep us busy other than exploring and building—both of which I love doing! 

My concern is that building, currently the primary thing many of us are doing while we wait for Mistlands, might be a total waste of time if the release of Mistlands effectively requires us to restart our worlds.  In such a case, all this exploring and building we are doing to pass the time right now would be for nothing.  Not only would that be incredibly disappointing itself, it would dissuade me from wanting to explore and build AFTER Mistlands came out, for fear that the same thing would happen with Ashlands, the Ocean, and the Deep North.

Therefore I would really hope the developers have, or find, a way to add these new biomes while allowing us to keep our existing worlds.  

Perhaps when a new biome is released, all explored areas of that new biome can be immediately “unexplored” and the fog of war re-added to the map for those biomes.  All existing structures within that new biome would be destroyed.  I think that would be a reasonable way to handle the addition of a new biome without having to start a new world.  I don’t want the massive base I’ve spent 200 hours building in the black forest nowhere near the Mistlands to be wiped out (by having to restart my world) just so that the areas of Mistlands I have walked through already can function properly.  

So, I really hope to see a mechanic like this—allowing me to keep playing the game today and building today and exploring today, while not having to worry that what I’m building today will be all for nothing, so to speak.

I’d love to hear other ideas from this community about how to handle such a situation.  Perhaps our solutions will spark an idea for the developers to implement new biome additions without requiring restarts.