Sad news, but this has become the trend lately. Shows announcing well in advance when they will end and working towards that instead of trying to hang on for too long. It gives the writer’s more of a chance to plan things out long term and not end up with too many filler episodes. But:

Another point is one that I would miss if Weiner follows through with his decision. The idea that Mad Men would take us through the 1960s into the next decade. So far, we’re still in 1963. There are seven years left of the decade to be reflected in the lives of these characters, including the entire counter-culture revolution, the women’s liberation movement, the Great Society and the Vietnam War. Aren’t you interested in how Mad Men would treat all that and more?

This is something a lot of fans/critics have said. There are so many things that are coming up in the timeline of the show that would be great to see them tackle.