I don't think anyone thought they would make a living from Amiga games but a nice boxed game could still be made. A few thousand euros could perhaps be raised via kickstarter.
What is the likely hood of creating a game for both Amiga and Atari systems, and any other similar platform?
If the game was designed to be easily portable could a theoretical 500 pre-orders be achieved? At 25 euros per copy that would be 12,500 euros. Some of this sum would be reserved for manufacturing as well as the game budget.
This all simply depends on how many pre-orders one can achieve. The only way to know is to do some research and gauge potential interest via forums and more importantly number of active hardware users etc.