Haaland is a big part of Dortmund right now. In the absence of him due to an injury, we saw how much Dortmund had a hard time beating their opponents. I mean that they had scoring problems more. Because Haaland has scored most of their goals I guess. Considering this fact, I think that Dortmund would be much weaker than now for sure if they lose Haaland to some other club. I'm pretty sure that Dortmund would do their best to keep him here this summer also but it doesn't seem probable to me.
It's hard to deny that Erling Haaland really contributed to Dortmund. He has become one of the most goal-hungry players in the Bundesliga. It is certain that Dortmund will try to keep him.
On the other hand I would like to see Halland play in the Premier League or at least La Liga. Let's see what Erling Haaland will decide.