[jltsiren]

I'm not so sure about that.

A federal state as a tight union of autonomous non-sovereign states is viable. We have plenty of examples for that. An EU-style loose union of sovereign states also works, if only barely. However, there is no evidence that a loose union of non-sovereign states would work in the present-day world. It might work, but the question is very complex, and we can't hope for a confident answer without actually trying it.

[xxpor]

We tried the latter suggestion back in the day, and it was terrible, even back then.