This is a concern and on should be skeptical, but we do need more data on what will actually show up.
We know there's going to be some sort of "battle pass" style feature, but the question will be what prices, content unlocked, and what will "missed" season/battle pass content be available later on if at all. However, given that Diablo 3 had a well regarded "Season" system that, while not leveled the same way a battle pass was, there is at least some precedent for how they could do it decently.
The biggest concern I have is if in addition to the pre order/special edition one off stuff + the battle pass/seasons, they'll also have some sort of purchased cosmetics/item mall or similar feature. That will definitely drop it down the toilet bowl, but if they avoid that path and don't fuck up the seasons/pass, it could come out at least decently as monetization is concerned.
Of course there are other concerns for game content and mechanics besides monetization For instance, the past two years has put Blizz titles in the hands of censor-happy political correctness advocates to distract from their now-settled court case investigation. I can hope that certain long standing elements or fun content of the past will not be sacrificed on the altar of twitter stereotypes making objections.