So knowing Blizzard he’s still going to be involved in Shadowlands because of course he is.
How do you want his story to end?
Realistically, he’s probably going to be a raid boss in the Maw raid.
Personally, I want him to, instead of being reunited with Sylvanas in the Maw, be simply among the vast amount of souls being tortured there, learning Sylvanas only cares about herself and doesn’t need him now that she has the Jailer’s foces, and he has to beg for our help after being heartbroken.