If necromancers are truly hopeless as a class, I’m kind of fond of the idea of merging the specific “necromancer as a caster” identity with the overall warlock identity. Necrolytes were thing in the Shadow Council, Old Horde, and the Burning Legion. One could really argue that necromancers are just warlocks that specialize in death magic. Gul’dan himself, after all, was a potent necromancer.
This could be accomplished by adding new abilities (preferably in the form of optional talents) that grant warlocks various forms of necromancer abilities, like summoning undead in place of demons. This would call back to the fact that warlocks are not strictly fel specialists, but will resort various forms of dangerous and forbidden magics such as void/shadow/and even sprinklings of death here and there. The Black Harvest quests had warlocks studying various sources of power other than fel and demons. There is no reason warlocks could not tap into the power of necromancy.
A class skin could work to, but that will always feel lazy to me (more power to blizz if they could make it work though) and a new spec feels somewhat redundant.
On the other hand I think, a caster necromancer spec for death knights could make sense as well.
There is a surprising amount of potential and lore justification for a ranged necromancer spec for death knights more focused on demo style summoning of hordes of undead while Unholy can keep the summoning it already has and maybe focus more on dots.
Lore wise, elite necromantic spellcasters summoning hordes of undead is literally what second war death knights were. Arthas was fused and armed with Ner’zul’s knowledge, and Ner’zul had some of those Death Knights serving him, so it would make sense to allow Scourge death knights to channel that second war style DK and focus more on necromancy where they might lack physical might.
Moreover, I would say it actually enhances current death knight lore. The lore for death knights is that they are fallen champions reanimated by the lich king during the 3rd and 4th war by Arthas and Bolvar respectively (Objectively superior chad 3rd war vet death knight player reporting).
The thing is, this only really makes sense to me if these fallen champions were warriors, paladins, maybe rogues and enhancement shamans and other melee classes/specs. Yet I think it is implied that these fallen champions could have been any class in life. It will never cease to bother me in this weird little way in how characters like Sally Whitemane go from a cloth wearing spell slinging priest to a plate armored sword wielding warrior, undead or otherwise. Sure, it’s perfectly possible to change your class in lore, that’s basically how we got paladins; however, becoming a death knight isn’t exactly like going from a priest to a paladin, it’s not exactly a job-change.
So, this idea of a spellcaster death knight spec is actually more sensible than most people give it credit for. It would make sense that death knights that were once spellcasters would apply the powers they were given in death similarly to the way they applied them in life, effectively reviving the concept embodied by second war death knights as elite, sinister, spellcasting, necromancers. All while fulfilling a frequently requested class fantasy.