@BillHarrison,
If we abstract your idea, you basiclly want to connect a modern x86 to the CPU bus of an Amiga. Then run a 68k emulator on the x86 so that the it looks like a 68k to the Amiga. Perfectly resonable idea and one I toyed with back in 2002... I expect my old posts are still in the archive here somewhere...
But now there are 3 problems...
1) As Piru has pointed out the market for this is so small it would be impossible to make it a resonable price, the cost of developing the hardware and software alone could NEVER be recouped.
2) Once you've built this new CPU board, you would want to add USB, a sound chip, a GFX chip, perhaps S-ATA (you pretty much get all these things for free with the x86 support chips)... then you have to ask yourself what is the Amiga actually doing? Why have I bothered to build an interface to the Amiga when everything is now offloaded to the new board...
3) On my machine at least (a MacBook Pro), it can, with UAE/WinUAE emulate any real Amiga I have... better than my real Amigas...since all output is by default on a nice monitor and via better audio... I don't have to use one of my aged Amiga Mice with the dodgy left click...
In short, it would have been nice 8 years ago... but not now :-)