Blizzard have already started to post (some of?) the changes in patch 2.3. Here are the mage changes, as currently posted:
- Fire Ward and Frost Ward now gain additional benefit from spell damage bonuses. Base absorb values of ranks 5 and 6 have been reduced.
- Ice Barrier now gains additional benefit from spell damage bonuses. Base absorb values of ranks 5 and 6 have been reduced.
Assuming Blizzard don't reduce rank 5 below tank 4, I would guess around 900 base for rank 5 and 950 base for rank 6.
An optimistic scenario is that a mage with +800 spell damage will get 400 bonus absorption. Such a mage will have a rank 6 Ice Barrier of 1350 - around 200 more than currently, give or take. That's a big help when farming mobs or normal 5man, a lot less help in heroics or raids. Still, overall, a very nice change.
If the base absorb is reduced only slightly and the entire +spell damage goes to the absorption this will give, depending on the mage, around 2k damage absorption. This will make PvP mages very happy and all other PvP-ers very angry :) so I doubt it will go that high.
- Detect Magic removed. All players may now see their target's beneficial effects at all times.
- Arcane Meditation (Arcane) increased to 10/20/30% mana regeneration.
- Evocation now regenerates 15% of total mana every 2 seconds rather than increase Spirit based regeneration.
- (NEW SPELL) Ritual of Refreshment available on trainers at level 70.
- Improved Fireball: The reduction in damage coefficient caused by this talent has been removed.
- Improved Frostbolt: The reduction in damage coefficient caused by this talent has been removed.