Since Sam was already back in the Castle Black in the finale of last season we don't have separate arc for him and most other end book stuff happens from Jon's perspective anyhow, including surprise appereance of Stannis that was already built up in last season and now he only needs to "surprise".
Escape of Sansa, Purple wedding and the following duel will probably happen at last 4 episodes with last episode being Tyrion escaping so that keeps King's Landing events overall quite confined and with our favourite Khaleesi having only one city left to conquer/govern/pass judgement those things get more cohensive pacing. First half of season is most probably spent fleshing out our beloved Dorne chaps.
Beyond that they really have Arya/Hound storyline which will probably be stretched over the entire season and her finally getting over sea is sort of "climatic thing" as with Tyrion's rescue.
Overall I think the starting setup for the last season of Storm of Swords can launch with great opporturnities for better editing and pacing overall