There actually is a Genesis 3(Megadrive for the guys from Europe) that we still have for sale here that I have seen at KB Toys in the mall. It is a very tiny little machine and plays the original Genesis carts but doesn't support the SegaCD (aka MegaCD) or 32x expansions if I remember right. It is similar in shape to the Genesis 2. Check it out here:
http://www.vidgame.net/SEGA/GEN3.htmlThen there was also the Nomad, but it was horrible because of the battery life just like the GameGear. Sega jumped the gun on technology too often and it has bit them hard...hmmm sounds kinda familiar.
As far as the drawing power a tiny all in one Amiga would have , I would have to say it would be pretty small. Lots and lots of people remember the Atari and Intelivision systems because they were literally the first consoles you could buy to play games on at home. Even if you didn't own one you knew somebody who did...at least that is how it was with my family and friends when I was very young. I don't know that the nostalgia would be there for an Amiga the same way. (Or the C64 for that matter) I am sure all of the Amiga's custom chips could be fit into a single chip along with a 68k, but really there is a lot more to it than just getting the designs, reworking them to fit in one chip, and producing the thing with a couple games in a ROM. Maybe most importantly, every all-in-one system mentioned before is a cartridge based system where all of the games were meant to be played out of a static memory. Our Amiga's had no such tech in them and thus you would have to rework the software to behave in a ROM not to mention make the new Amiga-chip think it was talking to a floppy when it was really accessing the ROM. A little more than just telling the CPU to start program execution from a different address in the ROM like what I would imagine is done with the Atari or Intellivision systems. But who knows.
At any rate, though I am sure many of us on here would buy one for $20 that I see the similar systems in the stores selling for, I don't think a lot of others would because unless you had owned an amiga and a particular game you used to love was on the new all-in-one, what would be the point? Everybody knows Pac Man, Pong, and Asteroids...not too many are going to know Amiga games because they didn't see them in arcades of the 80's.