So I was just testing out some numbers a moment ago in regards to armor levels now vs. what I believe they will be after patch 3.0.8.
From what I determined, I am going to lose about 5.5k armor from the change to Bear armor, and it not being multiplied by trinkets, rings, necklaces, and staves. My calculations were assuming that the bear form multiplier is calculated AFTER the new 66% increased armor contribution from SoTF (which is actually a best case scenario).
Now I am not in uber gear. I have primarily blues from 75-80 instances and some crafted gear. I did focus on having armor on all of my rings, necklace, and stave for tanking. However, I do not have any trinkets with armor on them.
I really hope my calculations were done wrong ... because I'm sure losing more than 5k armor is going to hurt, big time. I have already been told by a friend that Druids aren't really viable tanks in Heroics at present without really good gear. He may have been wrong ... but now I am certainly worried.