Today there should be a next generation Amiga OS we could be using. Of the three Amiga-like OS, none of them are next generation. At best there is one maybe 1990s OS, and the rest are 1980s OS trying to live in the modern world and all three are failing at it while the Dev pool shrinks a little bit more.
Look what happened to the two leading 80's and 90's OS'. Microsoft droped Windows for NT and rebranded it Windows. Apple dropped System for Mac OS X.
Are we willing to drop Amiga OS? We could keep the userland desktop or got for a work/look alike with a modern kernel underneath. Apple has shown it can be done. Doesn't have to be a borrowed kernel like Apple has done. It could be completely written from the ground up. Sort of a modern version of the Amiga microkernel. Though it would take longer.