I'd say concept album because they commented on it being an interesting possibility quite a few times on interviews during the last tour. Then, I agree with Sycsa and would say it will have the best MM drum sound yet (here goes hoping he takes some involvement on that side of things). Since JLB is not writing an album at the moment, at least not that he has made public, he can write lyrics this time around. If it's a concept album, I see them being a bit more experimental and out there than on DT12 and most of ADTOE - not experimental in the way they'll abandon their traditional sound because they've pretty much stated they won't do that (which is sad), but in the proggy, blow your mind sort of way.
And God please no djent. I love the BitS or Awake sort of heavy, TEI was great, let's keep it at that level.
EDIT: Also, longer songs than on DT12, which has pretty much been confirmed by JP when he said he finds it difficult to write short sungs. Unless he's up to the challenge.