Well we know Tyrande will be kicking around and still on the Sylvanas hunt in the nature zone.
I can definitely see Sylvanas being beaten at around the WOD Garrosh timeframe, yes. I feel confident at this point that they intend to keep with the "frustratingly similar story to prior expansion even without the same events playing out" thing we had going on in BFA with the Garrosh parallels. Though with her out of Warchief I'd imagine something else, maybe LK parallels?
Due to not being an alternate reality I don't think it will be as alienating as WOD where it's like "welp, what we're doing doesn't matter!" but more in the MOP exploring Pandaria feel where we're exploring a new place with its own stories with low connection to our existing ones.
Good? Bad? I dunno, I get that feeling during most expansions. BFA and Legion I'd argue were the most personal ones of the bunch, heavily focusing on Azeroth, with people and places we had previously encountered. Maybe that was a good thing, or maybe we need to shake it up with these alien new themes. I'm not a game dev.