There is a very good reason why we can't do this: you can buy technology, sure, but you can't buy a userbase.
Even if you invented an amazing killer machine it'd go almost unnoticed and would be out of date a week later anyway.
The days of bespoke hardware for computers are long gone, that won't change because technological evolution is what pushes competition in the market. Take out the hardware progress and you decimate the revenue - makes no business sense.
Incidentally, the Xenon/Cell CPUs are not suitable for desktop use, they don't have basic things like branch prediction, so will be a lot slower than you'd expect running generic software.
Keep the Amiga as it is - a minority platform uncluttered by the monstrosities of DRM and protection systems - and enjoy it for that.
