I personally think that a level 91 should be added to the game, as well as in the next expansion a level 96 should be added, and so on and so forth:
Why?
I THINK that if you have become SO, SO well accomplished say: with factions such as the Black Prince? (maybe make rep gains with the black prince another 25x harder, maybe?) That you SHOULD have the opportunity to have an early advance to the next level of play, possibly linked up to some very complicated and incredibly difficult quests and scenarios, POSSIBLY within the difficulty level of trying to solo a level 90 Heroic, at level 90.
Mounts? Sure, they show you how well you're doing dungeon wise/daily wise.
Titles? Sure too, keep them, they show that you're competent! you're a deadly slayer of foes!
A LEVEL ABOVE YOUR COMPETITION? Insanely awesome, insane.
I'm not saying this should be given out freely to every noob, I'm talking about - even at the end of Pandaria, and the lead up to the next expansion, this, one ability will be SO INSANELY HARD TO ACCOMPLISH, that only the VERY best will EVER accomplish it.
Obviously, this comes with a few benefits, level 91 wouldn't give you a huge, INSANE rise in your abilities, It would Instead lock some one of a kind armor sets, similar to the challenge dungeon sets, maybe a permanent height increase? Maybe some honor-guards that will always follow you around? Some really, insanely amazing shit. Custom responses when guards see you (See ashbringer SM reactions) Maybe EVEN an elite plate for your character!
In pvp you would be downgraded to level 90, In raids you would be allowed to keep your level 91 status, and custom armor obviously, but no real bonuses above what you already possess.
Think guild perks, except only for you, all the time - on top of guild perks.
What's your opinion on this?