I think you've got most of it covered
There is a great website somewhere with the whole sordid history but it's a very long read, unfortunately I don't have the link.
My personal interpretation of events:
1) Amiga Inc are DOA, never did much worth mentioning.
2) Hyperion used the 3.1 source code and ported it to PPC, then added some minor updates. They did a reasonable job I guess but they have been incredibly slow to bring 3.1 into the modern era. It looks like OS 4.1 final edition may well be just that!
3) Eyetech tried to launch a new Amiga, it didn't work out too well...
4) MorphOS is still ticking along but has also had a very slow development life (same as OS 4)
5) AROS is another one to look into (an open-source attempt at OS 3.1)
6) Classic scene is still reasonably healthy, there are actually more Classic users than NG users (which says everything about the state of Amiga NG!)
7) FPGA's are a recent (and exciting) development
8) And there's also been some OS4 computers released over the years by ACube and A-EON
9) Lots of new Classic hardware has been released over the years (processor cards, sound cards etc) and new hardware continues to be released.