1. Spiritual Attunement
Right now, SA returns mana even if you are healed at full health. So SA and Vampiric Embrace have gone nuts. I think Blizzard will reign in SA by only applying it to actual healing.
It's actually interesting, because Heal-Over-Time heals don't tick if the target is at full health. So for a paladin, getting a HoT is worse than getting a direct heal, because you'll lose out on some mana.
All in all, SA working with overheals leads to odd behaviour, and I think that SA will get nerfed.
I think that very powerful temporary buffs are a bad game design concept. The problem is that a raid which is willing to pay the costs for these buffs is significantly more powerful than a raid which isn't willing. And this leads to a dilemma when tuning content.
Should you tune content for the buffed raid, knowing that you are forcing every raid which wants to suceed to pay for the buffs every time they try this content? Or should you tune content for the unbuffed raid, knowing that the buffed raids are going to blow through the content?
It's far easier to just avoid the question and not have powerful temporary buffs. You can tune for permanent buffs, such as gear, because acquiring such buffs/items is a one-time, gradual, process.
In WoW, the major items that exhibit this problematic behaviour are high end alchemy flasks and elixirs. I think that the game would be better off without flasks. Then Blizzard could tune content to a more permanent gear level, and this would make life a lot easier for raid guilds.
Now it would be harsh on alchemists, as their uber-items would no longer exist. I would suggest that they get something more permanent, perhaps very powerful transmutations.
Edit: Here's a random idea. What if alchemists could transmute magical items? You could take a BoP blue and transmute it into a couple BoE greens. Or maybe a lower-level BoE blue. Heh, this idea probably isn't very good, but it's something that isn't in the game yet.