As Austria I always leave the HRE and try to get rid of Sundgau because I don't need a small province getting me entangled in wars with people I plan to destroy later. Selling Sundgau is always a bother because no one wants to buy it until very late in the game. As France and Burgundy clash I always try to sell it to Burgundy if they are on top and yet they refuse, if the Swizz are doing good I try to sell it to them and they refuse. But the times I have managed to sell that stupid province there really hasn't been any logic behind it.
So will the AI be more clever?
So will the AI be more clever?