I have no idea what to expect in season 5 as far as the story (have yet to read the books), nor do I want anything big spoiled, but that seems odd to me. Bran's story finally hit the climax its been building up to across 2-3+ or so seasons, and it's just going to leave off at that? Bummer.
I guess that would seem to mean any of three things...
1. Bran's story from this point forward gets more complicated than they can dedicate time to in season 5.
2. Bran's story from this point forward is relatively minor and not worth the effort.
3. Everyone else's story has far more going on that is more important (or deemed so for the TV show) and will be hogging up screen time.
Probably a combo of #1 and #3.... though again I'm totally guessing.
Personally, while his story hasn't been my favorite through most of the seasons, I felt like it was just getting interesting.
EDIT: Ah, well, nevermind! (assuming that the above was just misquoted)