Who knows? I believe I heard Mistlands was the last biome they had to build from the ground up so one might expect future progress to be a little quicker.

"It was released in early access on 2 February 2021 for Linux and Windows via Steam,"

It's also good to keep in mind that in the not quite 2 years the game has been out it has gone from being a 5 person studio indy title to whatever it is today. While many people, myself included, may want more quicker from them I don't know how realistic an expectation it is given the circumstances.