I think if this idea is going to come to pass, then Paradox should take this opportunity to add some additional historical flavors to the game: Enclaves without military access or sea connection should eventually break off into splinter states through rebels, with special mechanics. They will all be guaranteeing independence of each others and their mother country from foreign invasion, but not against each others, to reflect the fact that in real life all of them will be nominally parts of a single country that are all vying for control. They will have access to something akin to the Unify China CB which gives cores on every province with a mother country's core that they occupy (which means that they can also use that CB on foreign countries that have mother country cores as well). They should have loyalty mechanics of their own that massively depends on legitimacy, so that higher legitimacy will ensure that your splinter states will stay loyal, while low legitimacy will guarantee that those states will be disloyal as all hell.
