It's just too bad that as cool as a 4-door NSX would be, Acura isn't the type to do it, if it was Infiniti or Lexus, then there's some chance.
But Acura could use something cool like it, brands need that sort of thing from time to time.
I really think it would be a great way for them to start curving the company into something quite versatile. Hitting the high end, exotic like market, a super-sedan, and everything down to you're entry level ILX or whatever. Appealing to everyone with the reliability of the Acura name that people know and love.
It works with the Aston Martin Zagato because the rear end is beefier than the NSX so it's not too weird to put in an extra small door to make it a 4 door. The same may not work with the NSX which seems to have a steeper slope in the back. Would just look weird IMO.
That rear passenger door on the Aston Martin Zagato extends onto the rear fender so it's not as large as what you'd see on a normal sedan. If the NSX can do something similar without taking away the roof curve then by all means but, I don't think it'd look that great and the rear passengers will be left with minimal headroom.
Also, the BMW M6 Gran Coupe is hideous but then again I may be biased as their grille design has always been hideous to me. their German engineering is outstanding but I can't get past the front facia.