Interesting article. I think at this point everything is speculation until we see how the war ends.

Russia invaded specifically because Ukraine was a defacto NATO state. If Russia has the upper hand when it comes to end of war negotiations Russia will not (IMO) accept Ukraine (even a smaller Ukraine) building up an opposing army AGAIN.

If a military stalemate is reached, then I expect a North Korea / South Korea type of solution between West and East Ukraine. Maybe Poland and Romania will absorb parts of Ukraine as payment for rebuilding those areas they absorb.

Anyway, at this point it is really just a lot of speculation, because the war is very fluid right now.