The key for success of the PC was that there was a open design. Any PC manufacturer could build a "compatible" PC.
I believe that it would be very clever to do the same now for the AMIGA.
Idea is good but I wonder what you could achieve with open Amiga design as in hardware.
PC was never really about 100% compatible HW design but companies just delivered x86 based hardware that could run MS-DOS.
On Amiga it would be enough that you can run Amiga software. It could be just Amithlon, Pegasos or Natami. Running real Kickstart 3.1 or MorphOS or AROS, does not matter. It is up to consumer to decide if he wants Paula audio chip (or compatible implementation), Soundblaster, x86 cpu, PPC, 68k, Radeon 7000, Voodoo 3, AGA, whatever. Natami maybe runs old demos and games while Amithlon does not but Amithlon has (had) other advantages.
Everything should go via drivers. Direct access to custom chips should be provided only for backwards compatibility.