I will cut through the bulls**t and get straight to it. Now that Howling Blast is down to an 8 second cooldown and Rime now having that 15% chance to refresh that cooldown once triggered, is it safe to say that Frost is going to stay at the top?
Now I know some of you will say no because of the Black Ice nerf, but do remember Tundra Stalker and Glacier Rot are now buffed to compensate.
Also, since DK tanks are a very active "popping cooldowns" class, Blizzard decided to nerf such cooldowns such as Unbreakable Armor and Lichborne. Not really THAT big of a deal; glyphs can compensate (ex: new UBA and IBF glyphs).
In the beginning we thought Frost tanking would die out in 3.1.0 but it looks like to me it will be still the strongest and most viable tanking class.
EDIT: This is my mere opinion on Frost being the top with facts to support it. REMEMBER this please.