Recently a bunch of the writers here were talking about all the changes we're seeing to various hybrid DPS specs. Retribution in the beta is known to bring some serious pain, cat DPS has been given some pretty sweet buffs, and Shamans...well, Shamans seem to be in a state of flux, but when is that not true? With tank AoE threat buffed, the need for crowd control may also be a thing of the past, thus eliminating one of the more annoying roadblocks to hybrid desirability in 5-man groups. For 5-mans, at least, hybrid DPS should encounter significantly less difficulty (we hope) getting a slot.
However, it was my contention that, for the purpose of raiding, it doesn't ultimately matter how much these specs get buffed. They could do amazing DPS, bring incredible buffs, have any number of raid-saving abilities, and fart gold on every crit -- but you're still not going to see a lot of hybrid DPS running around Wrath raids for one very simple reason: someone has to tank and heal, and neither job is sufficiently attractive to allow most hybrid players to come as DPS. When it's a choice between respeccing resto or the raid never getting off the ground, most players will respec resto -- and decisions like that tend to be fairly hard to escape. The next night rolls around and -- um, do you mind coming as resto again?
It's a somewhat sobering thought that the raiding fate of players who love being retribution or shadow, no matter how good they are, ultimately rests on how attractive the tanking and healing jobs are to others. Some of this is within Blizzard's power to fix -- it's hard to appreciate the beauty of a dungeon or the encounter design when all you ever see of it are the boss' knees and health bars on your UI. The rest of it, however, is going to be up to the playerbase. Not everyone quits tanking or healing for reasons related to the game itself.
I'm going to enjoy Cat form's increased damage and tricks in Wrath, but I'm not optimistic that cats will find more use in raids than bears. The viability of hybrid DPS is not ultimately a function of the spec itself, but rather the need for tanks and healers in what seems to be a permanent DPS glut.