It's never been an iconic warlock ability. Like death coil (a death knight spell that warlocks learned), it's a demon hunter ability that warlocks learned. It's NEVER been iconic for locks- it's just something they got. Ideally, they'd keep it and it would be renamed, because of course demon hunters need to learn it for reals. It's sort of their kit after Illidan metomorphed.
Just because they made a bad call by giving a demon hunter spell to a lock doesn't mean that they have to never make demon hunters.
I recall you around here at WoD time, saying much the same stuff. It wasn't correct then, and it isn't correct now. Demon Hunters should be coming up soon. If they aren't, well, bad on Blizz.