Originally posted by autumndragonfalling:

My theory is we will reattaching Valheim to the world tree as part of the endgame. This will have the side effect of clearing the mist from the Mistlands.

while I personally think that would be pretty cool, I doubt it very much.
Valheim is Odin's Alkatraz, it was disconnected for this reason. the fact that the bosses can be repeatedly summoned suggests that they are never permanently defeated and as such, Valheim needs to remain an island prison. I do agree that killing the Queen should clear the mist. more than that, every Dverger still living after the queen is dead should be available to hire for labor in some way. it's the least they can do.