Unless great strides of progress have been made for the ARM ports of misc. -UAE, I'd go for the same idea but for machines with the most mature emulation. Even if you work out some bundle-preconfigged-tested-emu-with-game scheme, they could still get a small pixly screen in the middle of their bigscreen phone with slick graphics, frame stutter, crash or soundbuffer-stutter.
I understand the ideas stands or falls with the exploding-mobile-games-market thingy, but... I also think the selling-potential of the Amiga game will become about the same numbers as regular newly-released games for Amiga, when they are put on the mobile games market and are compared to what is there already, for free or for cheap. Only Amiga lovers like us will love Amiga-games on iPhone etc, and then you could simply make an Amiga-game with higher CPU-requirements? That would broaden the market to 'everyone with a PC or fast Amiga' as well.
There's one exception I can see, namely addictive original games patched to work great with touch/gyro/wireless versus. But you'd have to choose wisely; for every Amiga-Marble Madness there's a Super Monkeyball with really a lot of extra niceties to it.
Now, these are just my usual 'I see these problems...1) 2) 3)' thing I do. I'll try to balance it back up now.
1. Using the emulation core is a good idea - for not having to learn a new language. But it doesn't alleviate one bit of the game-code. It runs a bit faster (maybe) (on some devices), but also reduces your game-gfx and music to OCS.
2. Selling on a hot market is a good idea - even if you're a small company and even if there are tons of free games on it. If people try it and like it, they will buy it for a fistful of dollars. If it's promoted, they might buy it without trying it, but not if it gets bad user reviews. So how will you make a game they can try and will like, and how will you make the game as good as what they're used to, so they will give good reviews?
This is not to say I can't see Amiga games being sold on iTunes or Android Market - absolutely not - but your idea depends heavily on the emu-makers. Is there even one that doesn't require 'jailbreaking' (or can even be downloaded at all from iTunes etc)? (Edit: but of course you would ask the emu-makers to bundle the emu with the game into an app, or it couldn't be sold. Nevermind.
Since Android is now bigger than iPhone, game-bundled-into-customized-emu is the most viable option, I think. I still think adding a few sound channels and tripling the CPU-speed to a less geriatric crawl won't make much difference towards 'normal' buyers liking the game more, though.