The capitalised Slaves to Darkness bit certainly makes you wonder. That's the Chaos Undivided moniker in AoS, but seems likely to get merged with Everchosen eventually.
What Lost and Damned units do we have now?
- Gellarpox Mutants
- Traitor Guardsment
- (New) Chaos Cultists
- Negavolt Cultists
- Rogue Psykers
- Traitor Commissar
- Traitor Ogryn
It's certainly forming a decent list and I've not even listed the individual Gellarpot units.
Warpsmiths could also be on that list; their entry in the CSM codex hints that not all of them are actual Space Marines, but Dark Mechanicus that have constructed a (mechanical?) body in the likeness of a Space Marine.