It's very saddening to see some people assume that cooperation is impossible, and thus it shouldn't even be tried. That dooms MorphOS to fighting on it's own against the real threat (people giving-up & taking the easy route with Windows, Mac, Linux, Android, etc). (And the same applies to OS4 & AROS of course.) I think AmigaDave has the right idea that MOS+AROS+OS4 stands a better chance of survival if they try to work together (only where possible of course).

OTOH, I agree that it would be a bad idea to try to target two OSes at the same time. On a complex project like this, it will simply make the job twice as big. Better to make the initial target as simple as possible (i.e. MorphOS 3.x only), so you stand some chance of getting it working. But AFTER that happens the source code could be shared, and attempts made by other people to get it working on their favoured OS (preferably with #ifdefs so that the same source tree could be used).