You guys made a great game, and of a genre that NEEDED a new game!
One thing I'd really love to see is a "Random adventure" mode
Basically, you set the depth, complexity, difficulty of monsters and/or traps, etc, and the game creates a dungeon for you to get through from top to bottom.
For the party, players make a "rogues gallery" of characters (maybe with a max of 12 or so). The player picks 4, and starts delving. Difficulty is tweaked a bit for average party level (as over several random delving sessions levels will build up) so a bunch of level 20 guys on normal would still have a slightly harder time than a bunch of level 5 guys on normal. I think gear would be random, but i think keeping it between different dungeons would make things too easy.
I realize it might not make as challenging a delve as the base game, but it would be a great way to spend some time in the deep dark.
Heck, I'd even buy it as, say, a $5 DLC.