They are absolutely continuing to work with the UI team (who, as far as I understand, are just modders doing a bunch of discounted/free design while Tarn still does the coding). Getting the Steam version working with adventure mode is what they're working on now.
(Their new developer seems to be more of an old-school low-level hacker working on performance and systems.)
That's really great news! I am so happy for them and everything they have accomplished and will continue to accomplish. It's truly an inspiration to me.
They have a roadmap on their site. At the historical rate of development, the game will continue to be developed by Toady until his death, upon which (barring suspicious circumstances) the game's source code will be released.