Dark Iron Dwarves and Zanadalari Trolls are the only 2 races that make sense
"The Drakkari have recently gone mad after they sacrificed their Loa animal gods in an attempt to fight off the Scourge. The Argent Dawn has returned to play a role in Zul'Drak as have members of the Zandalar tribe, who have come to try and save some of the Drakkari history before it is wiped out."
That is the Drakkari trolls from Wrath, so the Zandalari went there to help them fend off the scourge.
Drak theron Keep questline where the Zandalari and Drakkari trolls are turned into death knights
https://www.youtube.com/watch?v=SOoyaSdG6i4
"your betrayal of the Drakkari empire has born me a new army, your army" - Lich King
Zanadalari trolls and Dark Iron Dwarves should both have a DK class option and it would still be 100% in sink with the games current timeline."