How will Ret Pallies justify their raid spot?

After observing a rather...heated discussion on hybrid DPS, I've noticed that all the other hybrid DPS specs either bring valuable raid buffs/debuffs to a raid or in the case of Ele Shammies, scale obscenely with gear. Ret Pallies, however, bring no unique raid buffs that would be universally good, and I do not know how they scale with gear. Imp SotC WOULD be in the same boat as Imp WF for Ele Shammies, but it relies on the presence of a Tankadin to mean anything, whereas WF is universal. Buffwise, Imp BoM and Kings can be easily picked up by Holy Pallies.
Yes, Ret DPS is horribly gimped atm by the Sanc Aura and Vengeance bugs, but they won't always be. On that day, what reason would an RL have to bring a Ret Pally over a Holy or Prot one, or even another class? What do Ret Pallies provide a raid better than anyone else?
For my purposes, this is PvE only, and a "Ret Pally" is any Pally with 5/5 Vengeance.
Yes, Ret DPS is horribly gimped atm by the Sanc Aura and Vengeance bugs, but they won't always be. On that day, what reason would an RL have to bring a Ret Pally over a Holy or Prot one, or even another class? What do Ret Pallies provide a raid better than anyone else?
For my purposes, this is PvE only, and a "Ret Pally" is any Pally with 5/5 Vengeance.