Yeah, I think Jackson would like to end each movie on a satisfying conclusion instead of leaving a cliffhanger; in AUJ the tone was deliberately made lighter with Thorin finally accepting Bilbo and the 'I do believe the worst is behind us' speech. Like Fives said, I'm going to guess that DoS will probably have Bard killing Smaug, the Company celebrating at his death, and then preparing to explore the halls for treasure and the such.
I doubt we'll get 8 sets though.