We now have 11 classes that can bring basic, essential and common buffs to the party/raid and I will deduce this situation is balanced at the moment. So, by taking the previous assumption as granted, I believe that a support spec should not interfere with these buffs but instead be worked around unique buffs that are not homogenized and don't affect the current ones. With all things considered, support specs were made to have rotations that enhance their buffs as opposed to the other classes that revolve around dealing damage or healing or taking damage with their rotations and in which the buffs are just a bonus(remember I am talking about party buffs not self-buffs). This way, the support role would focus their rotations on providing buffs in disadvantage of damage bursts or defensive abilities etc. and limiting these to very specific benefits so that no support spec would be superior to others in more than one chapter of its abilities. Of course they would need to have basic dps and whatnot to get around doing quests in solo or survive in pvp but these would be very underpowered and secondary compared to the other classes, but should work just fine thanks to the self-supporting abilities, anyway.
As a way of integrating the support spec in raids and dungeons and as I explained before, each support spec would bring unique benefits to the team, but since these benefits are limited to a short range of players due to not only the limit of targets but also the allies’ own specifications and unless the team consists only in either melee dps or only ranged dps or magic dps or slow plate wearing dps etc., a good pair or trio of different support specs will always be a good help. In LFR/D, this problem does not even present itself in my opinion, as its integration on LFR/D is easily manageable by making a requirement for support specs in a party and because a support spec would be useful in challenge modes and heroic dungeons.
The second part of the support integration in the game, is that each spec has its specific role in a party/raid because they are good at doing one thing and bad at the rest. Bringing dps brings damage but cannot help in anything else. Bringing healers can guarantee the survival of the team, but not the death of your enemies. As tanks go, we can count on them to take the damage and get the attention of the enemies but the rest is up for everyone else to do. As a support spec, the only thing it can affect the game is in supporting, whether it be by actively participating in the dps conflicts, staying aside and stepping in only when the tank has been mind controlled or worse, or help the healer by improving its range and/or effectiveness, but obviously it cannot compete with the healing, dpsing or damage mitigation of others, which is a good thing, as it keeps things balanced.
The third advantage of a support spec in wow is, again, its help in filling the missing buffs that I mentioned before as the common ones and, with some mastery and skill, improve either the dps or the tank or the healer. As I said, a support spec's range of skills is very limited in terms of classes so they do not bring buffs that can benefit the entire party in equal effectiveness so it means players would not just limit themselves to passively bringing the buffs while sitting back and watch the others do their parts.
Fourthly, a support spec works good in various other games, so why not take what's good from these games and add it to WOW? Fifthly and Finally, I think this would shake the game up and be really cool to play with and against.
So plz, any counter arguments are well in order and if you have none then I will rest my case Thank you very mucho ^^.