I don't think Haaland will continue in the Bundesliga. If so, he will not leave Dortmund. He is more likely to go to another league, another team. My guess is Real Madrid can buy him. Benzema's seasons not long now. Haaland is a quality striker who can play for many years in Real. I also heard that Haaland wanted to play for Real Madrid.
The pressure on Haaland in Dormund is much. They depends on his mostly in scoring goals. It won't be a bad ideal if he goes to another team, it will probably help as it will introduce him to new challenges, while he will further his career. Real Madrid won't be a bad choice, he will link up with Benzema, and also strengthen their squad. But I prefer his play in Manchester City, where he will spend more time playing in Champions League. But, if Haaland eventually leaves Dormund, it will surely affect them , as his is presently their goal machine.
In Haaland's view, he will still be a player that will be talked about for a long time. We still have a lot of time ahead of the summer transfer season. It is still uncertain which team he will go to, but as you said, he is the goal machine for Dortmund at the moment. Dortmund should start working now to replace this goal machine. I don't know which team Haaland will go to, but what I do know is that he will leave Dortmund this summer. I think he will be a player who can be more useful for Real Madrid.