Paladins where "created" during the second war to fight the old Death Knights (Teron Gorefiend among others) and their undead minions. They were a combination of Warriors and Priests.
Since Paladins are created to fight the unholy undead; Forsaken Paladins can not happen. They would have to fight themselves...
The Blood Elves (or the Blood Knights) did steal the light from the Naaru, but now they worship the Sunwell. As do the rest of the High Elves/Blood Elves.
The Tauren worship the Sun (witch could be seen as some kind of "light" that the Humans worship) and since they are great warriors, Paladins have merit within their culture.
Orcs were in nature Hunters, Warriors and Shaman. With the corruption of the Burning Legion the Shaman became Warlocks. The Orcs can use sinister powers (Warlock, Rogues) but they have never worshipped a deity such as the Tauren, Elves, Human, Dwarfs, Dranei or Gnomes do. Therefor they have no priests and thus as well no Paladins.
Since physical force and appearance is revered within the Orc culture, it seems highly unlikely to ever see an Orc priest.
Just my opinion though.