Originally posted by DeMasked:

One could possible expect a number of changes to current "finished" biomes and maybe some tweaks to the Ashlands or Far North. Mistlands will be the largest update since Hearth and Home or the ice caves.

I'm afraid the only changes occurring to "finished" biomes will likely be related to Mistland changes collaterally. One of the devs recently pointed out that updates to existing biomes shouldn't be expected at this time. It was actually here on a steam thread, might have been Smiffe.

And yes Mistlands will likely be the biggest update to the game to date , for sure.