I'm not going to really consider Arcane. I hate that spec with the burning fury of a thousand suns, and if it stays to the ground I'm fine with that. Someone who likes it can suggest something for their awful rotation and absolute and total lack of mobility in another thread.
Fire, they've at least acknolwedged that Critical Mass design is a problem, and are considering some suggestions for a better crit buff system.
Here are some suggestions to fix frost's problems with stat scaling and damage:
Mastery is the real problem - it's stacked in pvp for burst damage on player health in a short window, but translates into bad sustained damage only buffing procs and pet damage in pve.
One obvious solution is to split apart the percentages/effects like the Disc mastery change, perhaps add some to it. If mastery also increased say, frost bolt and mage bomb(they already can't balance frost bomb for pve+pvp, adjust it for pvp again as necessary) damage you could adjust the scaling between bolt/bomb/pet damage and the proc/frozen damage to get the stat to scale sustained damage without straight out wrecking people more in a deep freeze.
Another simple idea: consider adding mastery giving a % chance for your frostbolts to treat the target as if they were frozen. This will have negligible pvp impact - frostbolt casts are minimal, and if cast into a deepfreeze they can't count as frozen twice. It would add scaling to all 3 stats in pve though, with the mastery for +chance and +frozen damage, +crit to cap for shatter on the proc, and +haste for more of them.
Lastly, something has to be done about pet freeze. You've taken a janky pve mechanic of using an aoe reticle to generate single target procs in a boss fight, and made it even jankier by having it work only for some adds. Hurry up and add water jet, make it a simple single target damage + 2 fof procs to compare to the freeze shatter + 1 fof charge of freeze, and spare us this mess.