Atm high end 10 mans are running Disc Priest+Mistweaver and nothing was done to change that. Blizzard's nerfs so far were only for us, until Discs+Mw Monks will get nerfed there is no reason to change either
Holy Paladin utility is brought by all the Paladin specs, utility like 200k Revival(non crit),Damage,etc is only brought by Mistweavers. I doubt Blizzard will repeat the mistake of tier 15 having debuffs BoPed of.