I would want it to be AROS with seamless UAE integration. :lol:
Or maybe Clone-A or Minimig with AGA support, truecolour graphics, flickerfixer, scandoubler and a fast processor.
It wouldn't really need to evolve much from my current A4000 setup, as most of the software I run was made more than ten years ago. USB would be nice, however.
I would definitely not want an Amiga-in-a-joystick thing.