I think Haaland and Sancho are the players who do a really big job on attacking and there is a possibility for them to leave the club at the end of the season.
That's true and that's the dilemma of dortmunds strategy of buying young talents. There are 2 possibilities. A: The talent is not progressing as dortmund hoped and they have a young player that they don't want anymore but which they also can not sell for a decent price.
Or B: The player progresses as hoped and delivers great performances, but this also means that he leaves dortmund for the really big clubs like bayern, madrid, barca or the premier league teams. This whole stratey can't work out in the longterm in my opinion.