So I do not see a pressing need to coin a term that will
label us as a split-off from the real GNU.
I agree with you: no new term except GNU Assembly.
As for a term for legacy GNU "structure", I think you're right, and we will
just have to wait and see how awkward the communication becomes. For now we can just use
various periphrases like "the GNU maintainers who are not part of the Assembly",
and we'll see how awkward that gets.