From what I heard the finale is supposed to have Don today. Out of touch. Perfect for 1960 but totally archaic and unable to relate to 21st century advertising. Hell, he'd be 87 or 88 today so it's not totally outside the realm of believability that he would be the chairman emeritus of Draper/Olsen Advertising and he'll die at his desk.
I'm still pretty sure the story will end the same way the opening credits have been showing us it will since day one.