To me, this is the most exciting feature of WoD I've heard so far. Keep in mind it's just something they're working towards, so it could still not happen.
Bashiok's post today:
Frankly I'm surprised it wasn't this way from the start. Much as I understand WoW's systems are complex, I can't help but feel this was an excuse and some sociopath in the early days really just liked the idea that players might accidentally get flaggedThe systems that can cause someone to flag can absolutely at times be involuntary, which is notably frustrating.
In any case we are continuing toward a goal of a PvP on/off toggle for players on PvE realms to be added in Warlords of Draenor, which would absolutely and in all situations allow someone to refrain from becoming flagged regardless of their actions. Heals toward flagged players would fail, coalescing to PvP realms wouldn't be possible, misclicks and AoE's would never damage a flagged opponent, etc. It's actually quite a bit of work because of all the systems involved, but it's still something we think PvE players should have, and how the game should work for them.