What exactly is this rock, paper, scissors relationship anyway? Because what I see is two pairs of scissors and a single rock. Dark Knight and Warrior are both offensive tanks, which should be fine. But, both Dark Knight and Warrior lack the two things that Paladin has: utility, and now damage, assuming these values remain mostly the same. (Never thought I'd say that.)
Both Dark Knight and Warrior currently have one confirmed utility ability each. Warriors have Maim, which is a slashing debuff. Maim is unfortunately not as valued, since only Dark Knight and Paladin benefit from it now, and only if there isn't a Samurai or Ninja in the party, since both Ninjas and Samurai apply slashing resistance debuffs in their main rotations now.
Dark Knights on the other end, have the Darkest Night as their sole confirmed form of support. The Darkest Night, for all intents and purposes, is an adloquium-type effect. This works considering Dark Knight's flavor, lore, and all that, it functions as a polar opposite of Clemency. However, this is far from an ideal ability, since it can be self-cast and is tied to the Dark Knight's damage output, reducing their strength as support and causing this move to be used on cooldown, as stated.
This leaves Paladin with a venerable monopoly on support abilities. They have Clemency, which functions as a "Cure II;" Divine Veil and Passage of Arms are both incredible party-wide mitigation abilities; Intervention in many ways is a better Cover, while Cover is nothing to laugh at either; and this is to say nothing of their remaining monopoly on GCD crowd control, which seems to find a home in every expansion.
Additionally, Paladins possess an iron wall of defensive tools. Passage of Arms functions as a second Sheltron, which is already now a second Rampart; Sentinel is still stronger than both Vengeance and Shadow Wall; Bulwark is stronger for burst damage than the "new" Anticipation, and always was stronger for burst damage than Dark Dance; and do I even have to mention how disgusting Hallowed Ground is when compared to Holmgang and Living Dead?
So please, inform the crowd, what exactly do Paladins not do that Dark Knights and Warriors do?