Dominant future AmigaOS? MOS vs OS4 vs AROS

[AmiGR]

AROS is an Open Source reimplementation of AmigaOS 3.1, adding many features to the API.
MorphOS is a modern AmigaOS compatible OS that
extends the API quite a lot and had many stuff
needed in AOS for years. It shares some code with
AROS. It's released right now.
OS4 is the official PPC AmigaOS update that does
pretty much the same as MOS, but was started much
later, uses a different implementation and is not out
yet.
About differencies to the user interface etc., I'll have
to see OS4 before I comment.

[AmiGR]

Well, most up to date apps work, anyway. The
software bundle will have replacements for some
other needed stuff.
We'll see how it unfolds.
It's not as if it's not possible in MOS, they don't wanna
do it, for speed reasons and in order to keep the OS
clean. It could be implemented by a third party, like
on AmigaOS, for example.