@Thorham
While the 68020 is capable of better OS functionality, I doubt that it's going to help. Most of the extended addressing modes are slow on the '020 and '030. The '040 and '060 fixed that at the expense of some hardware compatibility particularly for floating point.
If Amigas are going to go anywhere, then a new OS+software is needed.
Also, memory protection would slow the real Classic Amigas to a crawl.
Depends on how it's implemented ('030 MMUs can do some neat things), and whether or not it's used for everything (it would be great to turn it on just for programming).
A better solution would be to build software on top of the PNaCl (Portable Native Client) sandbox that is going into the latest Chrome web browsers.
Two problems: 1) This doesn't run on Amigas, 2) What fun is it to write for a browser?
@Thorham: all your objection seems to come from the way you define "Amiga". You've defined it dead. Other people define it differently.
My definition of Amiga is hardware, namely chipset+680x0, and sadly this is dead until someone buys or licenses Amiga hardware and starts building the things, and that's most likely not going to happen

I'd love to see a new Amiga personally because I think of Amiga not as a thing so much as an ideology. Although it's also because I feel quite strongly that "the wrong side won", maybe it's just loyalty, but I can't accept that Amiga is dead and the prospect of a new market in ARM powered desktop/laptop/HTPCs makes me think that it has a real chance to get back on its feet again. If you don't want a new Amiga then, well, just don't buy one, fair enough.
My problem is this: Take the C64 and it's OS, now the Amiga comes along, and they put a C64 like OS on it. This is what's happening with the new alternative machines that superseded Amiga hardware. Those alternative machines are stuck in the past if they stick to the Amiga legacy, instead of just running an emulator.
Want an Amiga? Use/get one. Want newer hardware? Then move on, and do better (because there's room for a lot of improvement that won't happen by sticking to AOS).
And yes, I want a new Amiga, but no one will make one

I'll probably get an alternative machine after Amigas die physically (hopefully that won't be for another 10+ years...).