Dk's are pretty much all classes in 1. Snare, silence, gap closer, Dmg Reduction, and Healing
1. If they do want to bring a nerf to the class, I would say just like a paladins bubble reduce the dmg done while they are using a mitigation or absorb cooldown. However not by 50%.
2. Like how Rets Holy dmg is now basically physical, they could also do the same with Dk's.
I think the main problem with pvp is with mitigation, stuns and fear effects ( ex: fear > immolate > chaosbolt/conflag combo) that the dmg certain classes are doing is still out of control while the other person is not in control or their dmg is reduced or absorbed.
Just my 2 cents.