I did put up a poll on this awhile back:
https://us.forums.blizzard.com/en/wow/t/poll-what-class-do-you-want-to-see-added-next/775610
Necromancer is the pretty clear winner… but even if we put the theme overlap with Death Knights and mechanical overlap with Warlocks aside, I’m pretty sure the Shadowlands announcement, notably barren of any class announcement, was that ship sailing away.