I can understand the reasoning behind it due to the mastery system, but I am honestly dissapointed. They could just as easily have the mastery bonus change depending on your presence as hack talent tree up and mangle it so that blood is only tank and the others are dps.
That said, I -enjoy- cycling through tank specs (although my favorite is and always be unholy, even if it was murdered beyond existance by ICC dodge aura), and have done them all, and it's sad to see that go away.
I also find it incredibly awkward that given 'frost presence' is the tanking presence, talent tree-wise they pick blood. Now there's some dissonance. I mean, I understand how it'll take the least work since blood is currently already a pretty popular raid boss tanking spec with a lot of oh-shit buttons, most health, etc...but still, dissonance exists there.
Also, kitty/bear feral druid still exists. They've existed since vanilla. Is feral combat going to also become dedicated tank speak and kitty just lost his ninth life, getting wiped out of existence? If they're keeping the kitty, where do they fuse it into? Moonkin tree is dps, but it's also a caster, so that's even more awkward mix, and you can't really use same type of gear. But then maybe you can fuse moonkin/tree, they're both casters! ....Except then you're gonig to get outcry from people saying they like priests or pallies or shaman for having dedicated dps and healing specs. Either way, you're in trouble.
That's -four- types of specs on druid. With three trees, one spec would -have- to be wiped, if the mastery system is really an issue. You can't really mush two trees together, and then say DK can't do that too.