(The M from ASMB here, hi!)
It might! We've talked about it a few times but we want to be sure there's actually enough gameplay there to justify a full game! We don't want to fall into the same trap as NMS where there's an infinite universe full of nothing to do, but we're also not so hot on doing a bog-standard linear platform puzzle game either. We've had a few cunning plans but haven't had time to work on any of them yet :)
Currently the A, S and B of ASMB are working their butts off to ship Moonman by early next year as well, so there's that!