There's a no-go with an implemented core using the actual FPGAs that could outperform a plain 020 with AGA.
No. The fpgaArcade TG68 CPU with small caches and minimal pipelining is equivalent to a mid speed 68030 already. AGA performance has been surpassed in the fpgaArcade and Natami prototypes.
There's a no-go with real native hardware fully compatible with AGA, see the S-AGA on the Natami.
There were supposedly issues with the Natami design but it was an aggressive design that would have provided a huge speedup to AGA+. Improvements in AGA performance are achieved in fpga without even trying. Some things may even need to be slowed down to improve AGA compatibility.
At the end nothing like a new Amiga portable hardware will be made.
FPGA's can't achieve (for now) what we want at an affordable price.
Design new native compatible chips and bake them is stratospherically expensive.
It depends on what you consider affordable. An fpga can only be cost reduced so much but prices are constantly dropping while sizes and features are increasing. It should be possible to produce an fpga based board that will outperform any classic 68k Amiga for less than 500 Euros.
However, i'm not sure if someone came with this idea so far.
What about using a low-cost PPC as CPU, and have the video and audio implemented
in two different FPGAs?
Most low cost PPC chips are for embedded systems and limiting. The cost is not so low without large quantity purchases also. Separate video and audio fpgas would increase cost and complexity. I doubt there would be any speed advantage to separate fpgas either.
There is also the MCC 216. Multi Classic computer. Check out some of the reviews on that.
I'd like one. Perfect if you mostly play games.
I believe the MCC has an fpga that is smaller than the fpgaArcade. The fpgaArcade fpga is even too small for the Apollo CPU or an FPU with the Amiga chipset. The fpgaArcade should get the 68060 expansion board but I believe this would not permit the original handheld gaming design (if a proper case, LCD screen and controls were ever made). The newest version of the Mist fpga board (Cyclone III with 25k LE) has a larger fpga than the fpgaArcade. It should be large enough for a 68k CPU, FPU and advanced chipset with some cramming but has other limitations. All other retro computing fpga boards I know of are handicapped by too small of fpga including the MiniMig+.
