Ghostcrawler has said that Prot Warriors are going to be nerfed for PvP reasons. This is depressing - the most fun thing about Prot Warriors is the varied toolkit and mobility. It would be a shame if that went away because Blizzard are obsessed with their declining arena "e-sport". From what I've read on the forums it seems like its our ability to break roots repeatedly that's the problem, and I guess this is due to the Warbringer talent.
Let's hope they can find a solution which mitigates the perceived PvP "problem" without stopping us from zipping around to pick up adds in PvE - perhaps by making Warbringer only work in defensive stance, although presumably the better warrior PvPers would simply stance dance to charge or intercept out of the root (intercept only requires 10 rage, so it should be possible to dance and intercept despite the loss of rage, although since intercept does not generate rage it's harder to follow this up with a massive combo of attacks so perhaps less of an issue).
The damage thing is a bit more worrying - my dps is still pitiful even though my rotations have improved drastically over the last few months. Maybe (and again I am just making stuff up here) the damage of shield slam and revenge could be reduced when not in defensive stance, but this is just another layer of complexity for new warriors to deal with.
It's odd that despite the fact that DKs were supposed to be the "caster tanks", warriors are arguably better for tanking caster elites than any other class. DKs have death grip and a magic shield, but both of those are on a decent size cooldown. Warriors have the ability to spell reflect (which is still simply great against such mobs) and the ability to move quickly between the adds putting out threat on each via Warbringer. The four stuns (intercept, charge, shockwave, conc blow) help dramatically too. It's always the warrior who has to go prot spec and bully the healers in Faction Champions.
DKs are still great for tanking magic using bosses, since magic shield in effect becomes another mitigation cooldown whereas the warrior's toolkit is generally useless against bosses. Frost DKs also have Acclimation, one of the strangest and most mysterious talents in the game, discussed by Gravity here.