It seems that the current WotLK trend is to provide tank classes with a DPS stat -> Mitigation conversion in order to allow tanks to increase their threat (and see big numbers) while providing another means of scaling up their mitigation with gear progression. If you don't quite know what I'm talking about, Strength converts to shield block value for Paladins and Warriors and Death Knights get additional Parry rating equal to 25% of their strength.
With the current armor changes to Druids coming to the PTR, Bear tanks are scared of mitigation scaling issues once they have obtained a decent gear set due to the lack of large armor increases with gear improvements that previously existed and only having one other form of mitigation that diminishes quickly at these same gear levels (dodge).
Perhaps it's time to introduce an Attack Power or Strength -> mitigation stat conversion for Druids in a way such it will assist Bears in scaling appropriately in end game raid content and help them to regain some of their lost mitigation from previously high armor accessories (cloaks and rings in particular) that are now itemized more appropriately for the other three tanking classes due to their excessive amounts of strength.
I am currently at a loss of ideas for such an implementation; I am only able to imagine some sort of STR/AP -> Miss Chance or STR/AP -> Damage Reduction formula or talent as a solution to this concern.
Feel free to post your thoughts and/or implementation ideas.