Honestly they need to get rid of the mp cost of changing or applying stances.

Simply give DRK a group mitigation tool or get rid of the ones on PLD and WAR to balance things out.

Slashing debuff from WAR needs to be removed, especially since they got rid of PLD str down and DRK int down debuffs.

However I think WAR will continue to be the golden child in 5.0 and we will see tank balance continue to suffer whether they add a new tank or not.