My dream bike would argue persuasively with potential thieves, bringing them to see the error of their ways, so that it could be left unprotected anywhere. If it were simply booby-trapped, then I would sooner or later forget how to deactivate the traps.
Moving on to something more achievable, my dream *folder* would include an integrated luggage system that would not interfere with the fold even when fairly heavily loaded. And a way of rolling it around when folded, whether it was on Brompton-like extra wheels, or on one of the bike's own wheels.