Yes a new system coul help model in certain wars into the game such as the Catalan revolt when the principality of Catalonia that was backed by France tried to leave Spain and create an independent pricipality after being autonomous for 100s of years, or the Cornish revoltYes, but still not clear nor interesting enough, especially as it would still be very very narrow in covering some of the conflicts that did errupt.
It would also mean that French, English and other kingdoms fuedel domains can be potrayed as many where quite powerful and could even rival the king - an example of this would be the war of the roses
Later in the game it could then model in European powers colonies and trade company's that usually had some self rule