There is NO money to be made out of classic Amiga stuff....period... the end.
That boat sailed long ago. Is it still possible to make money on Amiga games that are new? Yes, probably, but not in comparison to the effort required to make the game.
The problem you have is HISTORY. If you want to write a game on a classic Amiga that will get people to dig their hands into their pockets and support you, History would say you're not likely to succeed.
History? Put simply, if you're going to write a platformer and expect people to buy it, its got to be comparable or BETTER than what preceded it.
Have you got it in you to compare or beat the likes of Turrican 2? That was a 5+ man team effort, that took nearly a year to realise, oh, and you've got the likes of Chris Huelsbeck to compete with as well. Bummer!
Or maybe you'll opt for a later market platformer. Wrong again. Brian the Lion, 5+ man team again, ex-demo coder heading up the project to make it as console-esque as possible, took over a year to do.
And you can apply that logic to virtually any game you're thinking of doing, people are ALWAYS going to compare to what came before, its human nature.
Its why PHX's Solid Gold gets a free pass, because it was FREE, it circumvents the need to be compared unfavourably with previous games, because theres no payment.
I'm avoiding that by converting Atari ST games that never got released on Amiga first time around, I don't have to make them fantastic, the fact they are getting a release is enough for most people, and the audience for Amiga stuff right now would probably appreciate it more than if the game was actually released 20+ years ago.
However, AlexH touched on something which I kicked off as an idea before, which was to write an Amiga game, but use an Android Amiga Emulator as a wrapper to bring your game to a wider audience and charge for that.
Are smartphones more powerful than classic Amigas? No doubt, but a good game is a good game, plenty of Amiga games untouched wouldn't look out of place on Android or iOS.
But as for making money out of a standalone classic Amiga game......you're too late, by a long time, Christ, Speris Legacy was too late and that was 1996.... your chances are LESS than zero.
Facts suck, but suck them up.