I wonder where they are gonna go next season. Will Walt and Jesse continue cooking Meth? But maybe this time, they work for no-one but themselves. That is the only way I can see them continuing to cook.
Or maybe Walt and Jesse will leave the business and attempt to get their lives on track to a crime-free life. But in the process they encounter old enemies. The Cartel might be an enemy in the final season, with the DEA taking a larger role and potentially Walt assisting them with what he knows.
A lot of people are also predicting a Walt v. Jesse showdown for the final season, which is possible; especially if Jesse finds out Walt poisoned the kid. But at this point I would find it strange if Jesse wanted to kill Walt after it was over and done with, and the kid is fine and Gus is dead.
Interesting contrast how Season 3 ended with Jesse killing someone to save themselves, and this time around it was Walt doing the killing to save them.
I was expecting a cliffhanger ending, but as Vince Gilligan mentioned they don't know how the show is going to end. So I figure that factored into the ending without a cliffhanger. This way when they begin writing in November, they can literally start a new story from beginning to end. I have ideas where the show will go in the final season, but I have no idea how it will end.
Another great show coming to an end, I'd always have an end date set ahead of time though. It makes a better story as a writer to know when it will end, and it's great that we get three extra episodes for the final season (16). Although I heard the final season will be split in half, something like 6 episodes first and then the final 10 a few months later (I think AMC is doing the same thing with The Walking Dead?).