Although, I've always wondered if Patrick could meet Cam's family (if they were "clan mitchell"-crazy, Patriotic to the core, and ultimately accepting) if he would have reconciled (or maybe headded of the disaster that was their big fight) with John.

I'm not entirely sure that patriotic to the core would really have appealed to Patrick. Maybe the ultimately accepting would have won him over, but as you say, I think John gets his stubbornness from somewhere, so maybe not. And I'm really not sure he would have given them the chance.