FPGA ftw!
An x86 on a card running an emulated 68k that appears to the Amiga as a real 68k CPU is a fantasy I've often dreamed of too. Theoretically it would be faster than any current FPGA tech.
Ah we can but dream eh?
Why dream? It is dead easy to accomplish, in fact I have already done it
I bought and ebox for about $150 (It is a very tiny PC), and set up a Windows XP + Winuae enviroment, then hid all the Windows stuff, so the ebox would seem like an Amiga. I connected it thru ethernet to my DraCo (You can use your own Amiga instead) and then used VNC. The DraCo was the client and the Winuae PC was the server.
I am not at home right now, if not I could show you the setup. Anyway, it is dead easy. You can also use, instead of VNC, RDP, or even X (all of them have been ported to the Amiga).