Currently haaland has a long contract with dortmund and the sporting director of dortmund has also said previously that haaland will not leave dortmund this january, but it looks like it will be very impossible for dortmund to hold off haalaand departure if any club is willing to pay him more than dortmund release clause later, I think dortmund will certainly keep haalaand anyway this season, but it looks like haaland has made up his mind to leave dortmund as soon as possible.
His contract with Dortmund comes to the end soon. In the next summer, the release price of Haaland will drop dramatically according to his secret deal with Dortmund. It will be a good chance and great discount price for other clubs to pick him out of Dortmund.
If Haaland creates pressure to leave Dortmund and other clubs really want to buy him, we will no longer see him in Dortmund after the next summer. There is even rumor that Haaland has plans to leave Dortmund in this winter transfer. However, I don't think he will leave Dortmund in this period and other clubs won't be ready to buy him as well.