The possibilities for Borussia Dortmund to keep Haaland are not so huge and are not comparable to such clubs as Real Madrid, Manchester City or even Barcelona with all their financial difficulties. Therefore, it is difficult to imagine a scenario in which a player will not leave the club next summer, so Dortmund should make full use of the presence of such a player and already prepare a replacement.
Maybe is not for the time because his agent Mino Raiola has sick. the agreement with (Madrid, City or Barcelona) will continue once he recovers. the last club is his wish (Barcelona), but it's hard because Barca has financial problems, he knows Barcelona will make him be a hero like Messi, that club is not royal to sell players as Madrid did. Regarding substitutes, Dortmund was found the potential player to replace him, Scamacca and Chiesa. but it's still rumors until they finish this session
I think Haaland is not trying move to other club on this window transfer although left one day only before window transfer close, He will priority for transfer on next season and waiting which one serious team will pay higher salary for him and Dortmund want to get higher transaction transfer. Just have two option for Haaland as serious team can give enough salary for him from Manchester City or Real Madrid, I don't think with Barcelona have enough money for paying Haaland transfer and he looks not happy with Barcelona still faced financial crisis right now, better move to Manchester City or try with Real Madrid.