You are right. Dortmund is called the club to grow young players and sell them for a huge price. Dembele, Sancho, Lewandowski are just a few examples. Haaland will be the same. He is already an exciting one in the transfer market for RMA and City. Since he rejected City, Bayern might also be a good place. What I think will happen is, Haaland will go to RMA, and if not RMA, he'll join Bayern and Lewandowski will go to either City or RMA.
Robert Lewandowski will have an opportunity to get out of Bayern if he wants to, I don't know if Bayern Munich can afford to pay two super goal scorers at the same time, and pretty sure Bundesliga will be imbalanced from there on and people will be tired of just betting for Bayern's nonprofitable matches, because of high odds. but who knows what may happen, let's just hope it went, good.