If none of the three are in there, then we're probably looking at a complete re-write of the game from the ground up. However, do you see many of the existing players sticking around if at least one of these items arn't implemented.
I would definitely not leave over any of those 3 not happening. Legs and base building I have so little interest in, they might actually make me leave if they are too integrated into what we already have (an amazing place to fly a spaceship).