I know that Real Madrid will do everything in their power to sign him because they really need fresh blood in their midfield. With Bellingham, their midfield will be stronger than before.
Of course, Real Madrid usually gets the player they want. The amount of money isn't a really big problem for them if they think it deserves the player. Now, they sign Bellingham with big money. We don't know whether Bellingham will strengthen Real Madrid midfield or not in the next season. There are many players who fail to shine in Real Madrid, one of them is Hazard. I hope Bellingham won't experience the same thing as Hazard.
Dortmund is used to letting their best players go once they profit from the deal, which is why I think they are still suffering to win the Bundesliga ahead of Bayern Munich. It is only Marco Ruise that is patient enough to stay at the club despite different offers from different teams.
Dortmund gets big money, they can buy some players with that money. Sure, they lose again one of their top players, but they are always smart to find a new rising star. Although they become weaker and more difficult to compete with Bayern Munich, I think they will find again another great player to replace Bellingham position.