Actually, such a product might be useful as a replacement motherboard that would fit in a variety of old Amiga cases. It could use old 68020s and/or 68040s pulled from ancient trashed Macs, along with old Paula and CIA chips (which never changed throughout the Amiga line). It's true that a clone AGA chipset would have to be built, but if most of the research and design were done as an open-source kind of side project it wouldn't be impossible. Some of the enhancements would be a fairly simple matter, too- it would be very cheap to throw in an audio mixer and IDE interface. It could also be made modular, with a central board having all the essentials for every machine that plugs into a simple extra board specific to each case having a variety of slots and ports.
It's also sort of been done before (there was a clone motherboard made for the A1000 called the
Phoenix). It wouldn't be any sort of high-speed scream machine or anything, just a slightly enhanced replacement for old and failing equipment. Think an Amiga equivalent of the C-One, but with nowhere near the C-One's level of crazy enhancements.
