Bout MUI:
MUI does exist in a useable and free form for all major "Amigas", you may not allways be able to use the setting in the unregged version, but thats all there is.
This version wouldn't disappear even if Stunzi decides on a drama-tantrum, it's native and new apps can be coded for till the sun make BOOOM.
In such a case you would have 2 kinds of SW:
1) things that aren't developed anymore, those also don't need a newer version of MUI.
2) things that are still developed, those could be reworked (with relativ ease) to one of the MUI-clones (Zune or even Feelin).
ReAction on the other side is only available for OS4 and (in an allredy moothballed version) 68k. There also next to no chance that the ReAction-API would survive the introducion of real MP without changes. You can just forget about binary-compability in that case.
All in all I would say that the future of ReAction is atleast as uncertain as of MUI, and that doesn't even take into account that most active&productive coders detest it.
MUI-classes also don't have to be a problem, just write:
- all used classes must be native and distributed with the main archive (unless found on OS4-CD).
- add blacklist for problematic classes here
