What if there was a plug in option for Agnus, has an FPGA to "Replace" the motherboard one (as long as it is SOCKETED), and associated RAM on the add on board to bring CHIP ram up to 8MB ?
That would be kickass, but you'd have to add a ham texture mapping engine to the blitter to really make it worthwhile.
It would be interesting to see if you could write to the denise colour palette fast enough to do something there as well.