As I said, the warlock has seemed to suck up all the air for "spooky" characters (and even then, the warlock patrons are angels, fey, fiends, and aberrations, only one of those is truly evil, making them more of the "play as a monster" class that the Next Sorcerer was going for.) I guess Aberrant Sorcerers are kinda edgy, as are assassins, shadow monks, vengeance paladins, and gloomstalkers.I'm really not surprised at the lack of 'edge' in the subclass selection.
I wouldn't have the same set of abilities (meaning minor name changes like "Student of Necromancy")Merging the schools doesn't work. There are too many subclass abilities to fit (at least 25 abilities with lots of wordcount). It would take up almost the same pagecount as all 8 subclasses.
Honestly we are due for an Undead themed book.I think the biggest problem is there isn't enough spell support for edgy casters. PHB-only Necromancers have few options and need Xanathar at the minimum to be anything beyond "wizard who also casts animate dead". Maybe a future supplement with necromancer, undead warlock, grave cleric, spirit bard, shadow sorcerer, spore druid, and appropriate spell and feat support to make them worth while would be worth the wait
Honestly I like this direction, though admittedly I'm not sure that the warlock is the best place for it. 5e has basically no options for 'play as the monster' characters, yet it's a common fantasy trope.making them more of the "play as a monster" class that the Next Sorcerer was going for.