I hear rumors about Erik Ten Hag wanting to buy Harry Cane(or Victor Osimhen) as a central striker and Franky De Jong and/or Jude Bellingham in the midfield. Bellingham, on the other hand, wants to join Real Madrid. The are offers to the Glaser family coming from different sides and I guess that Manchester United will have a new owner by the summer of 2023. This means a bigger budget and more money for new players.
Manchester United currently on their top performance, those players have nothing to lose to join Manchester United because they will get a lot popularity and their performance are good in their current teams. Dortmund, Tottenham and Napoli are just mediocre teams, just use that's team as the step stone to join the bigger teams. I believe the players will get better salary too. However Frenkie De Jong have been joined one of the best team in La Liga, so he can choose to stay in Barcelona.