From a PvP perspective.
With all the changes to existing classes, would shadowfury for all really be that big of a deal? It's a 3 second stun making it very short (just like our other "stun" .. deathcoil .. ) and I think it could end up being what warlocks need for pvp as well as not having to be destro for stuns in pve.
With all of the possible ways to remove fear, the short duration of deathcoil and the only way to hide being a premeditated portal, should all warlocks have the ability to stun regardless of spec to allow time to LOS or set up dots/fears?
With druids and shamans able to swap to cat/ghost wolf, holy palys with their sprint/freedom, priests with their anti-fear, it would help set up some offense on healers and hey, if they do get rid of mana drain we need some sort of edge on them.
This isn't a qq thread from some noob being owned in PvP, these are my thoughts and am wondering if anybody else feels that this should be. Would it really be any worse then ring of frost? No, because it has a shorter duration .
If not this .. then bring back tainted blood! Warlock pets get simply stomped by most melee and even with 3 instant casts .. it is often not enough.