These aren't the changes I think should happen, but they're realistic in terms of PVE/PVP balance
1) Remove this silence/stun component off of Ice Nova, mages don't like it, players don't like, result is that Ice Nova won't DR everything, perhaps replace with 3 second root. - Realistic because doesn't really change PVE balance, nerfing the damage slightly also likely since its a pretty auto-pilot mechanic and pulls ahead on single target fights, or possibly make it not benefit from Shatter.
2) Buff Comet Storm damage dramatically, remove splitting mechanic. Likely because CmS is garbage in PVE, and hits like a wet noodle in PVP.
3) Deep reverted back to stun that doesn't break on damage, this is probably a stretch though.
Thats about as far as I expect Blizzard to go with mages, I don't see them redesigning the class or removing and replacing talents at this point.
Of course, these are garbage changes that will make mages viable since they'll just revert back to being a huge insta-cast dmg class.
Some changes I would like to see, but won't happen
1) Evanesce is a stand-alone ability. Giving up Ice Block for Evanesce is a cool and interesting trade-off, but thats not the tradeoff here. You're giving up Blazing Speed AND Ice Block to get Evanesce, this kind of stuff really sucks and its hard to justify taking these talents in PVP or even in general. I'd like to see it benefit from Glyphs too, maybe IB glyph extending its duration by 1 second, or RI giving you the heal component for a few seconds. Some kind of cloak mechanic that removes debuffs here would be awesome.
Same treatment for Ice Nova as well tbh, being forced to use almost all of your novas offensively to generate pressure really sucks. ( Shattering for Ice Nova with pet, and obviously you don't get your own FN anymore )
2) Set bonuses....not sure what to do here, 4 set is backwards, so maybe reverse it, casted Frostbolts increase the damage of FoF ice lances by x% for each one casted. I think mages have a mana consistency issue when it comes to Spellsteal with the removal of Evocation and Mana gem, so perhaps successful FoFs generated grants a charge of lower mana cost spellsteal, stacking up to 2.
Some more things I could think of but I feel like this probably too long as it is