The "peripheral" countries mentioned in the GP were nations or at the very least distinct semi-national entities before the USSR.
States in the USA have no effective history before being a part of the USA.
Wrong, Hawaii and New Mexico ( which included parts of Arizona, Colorado and Texas) do
I do not think it will happen but this is why in discussions about this happening, or historical fiction, typically the places that break off are the ones that were distinct _before_ they joined the US. Any of the 13 colonies, New England as a block having the strongest colonial identity that I'm aware of, Texas, or California generally are where it's assumed to start as those were countries/had identities very much outside of the US while also having economies that might be ok.