Blood while boring at times is in a really good place for tanking, it could use some talent revamps but the core gameplay is solid and works well. My guess is next expansion is the big rework to most of the classes, they seem to do it every 2-3 expansions where they rework stuff from every class. Blizzard needs to stop worrying about revamping a class during an expansion, if it is under performing they need to just do it, and the only reason they don't is because of tournaments/pvp and bullshit e-sports literally no one cares about.
PvP is the reason you don't see specs and classes iterated upon often enough, there is no other logical reason to not be continuously reworking things until they feel right or fit the class properly. This is why they should separate and take the classes on different directions when you decide to PvP so nothing they do there effects PvE.