It might be an idea to have two different tracks for future Amiga development:
(1) A version which is Amiga classic hardware/software true. Ie if you can run it on a A500 it will run without modification.
(MC68060, FPGA chipset, etc..)
(2) A version that is brilliant in using technology. We won't compete with ATI/nVidia/Intel/AMD etc.. but we exploit existing chips in a clever and costeffective way. This version would not have any compability ties with original Amigas at all except in spirit.
(Get the most MIPS/Hz CPU, efficient GFX, FPGA subsystem, etc..)
One could exploit the SRAM feature of FPGAs by reloading it every 10^-3 second. And thus make it do many things with a small configuration.
As for a consortium. Collect data on A500/A1200/A3000/A4000 and put into a report that can be used for hw/sw developers for re-implementations.
An portable Amiga with a 7"-10" screen with super efficient use of battery/cpu/ram/periphials etc.. could be an area where it's possible to get at the competition.
A drawback we as a community have is the economy of volumes, army of optimisation engineers, budget for failed prototypes etc.. any project will have to make up for it in some other way. Once one can produce at least 1000 units. The producer is the king because you can order directly from manufacturers, not digikey/jameco/mouser and the rest.