Blizzard said they will remove about 20% of class skills and abilities to help address ability bloat.
Which warlock spells will they remove in WoD?
The following list is based on my personal predictions:
Curse of Enfeeblement: with the 5.4.7 nerf the spell is no longer worth casting
Curse of the Elements: this spell has no identity it isn't fun to use
Howl of Terror: With the cc nerfs the spell will possibly go back to a talent tree again, we may see Demonic Breath as a Demonology spell
Twilight Ward: (absorbs X spell damage) the spell is useful but doesn't have a special effect like the good old Nether Ward
Fel Flame: after the nerf of the destro version of fel flame the spell is no longer useful, it's just an instant spell that deals small damage
Bannish: is conditional but useful sometimes, it's the least used spell for me but I hope they keep it
Havoc: It has almost the same effect as Fire and Brimstone with the lvl 100 talent
Wild Imps : my guess is this spell will not survive in the next expansion, the glyph may stay or become a demonology spell
Metamorphosis: Void Ray : will be removed with fel flame
Malefic Grasp: I guess the spell will be removed and replaced by a buff to drain life damage
Curse of Exhaustion: This spell needs a buff I hope they merge it with Curse of Enfeeblement to make it a strong debuff for affliction warlocks
Agony: the spell has the same effect as corrption X damage over Y time, they will have to buff corruption if they remove it
edit: i made some modifications