I don't disagree that they need a new game. 17 years is a long ass time (too long) for one game to keep going, regardless of the expansions adding to it.
I personally think they will do (if covid didn't mess it up) what they are doing with OW2 in 10.0
Which means - Upgrade the game engine, textures, changes to how the game plays, new narrative (time skip), while allowing the original game (and all you're progress) to still function within the new game.
Yes, these are things an expansion could do, but giving the game a new 2.0 label communicates to people it's a different game and gives the developers freedom to do significant overhauls and take the game in different directions.