#2 Gianluigi Donnarumma
Gianluigi Donnarumma' saga with AC Milan has been like a couple eyeing for divorce but just at the time of moving away, the reconciliation process happened. He has signed a new contract at Milan last year but it still looks as if a top club can definitely lure him in the future.
Manchester United's gap if De Gea leaves will be a gaping hole that needs to be filled and given the healthy relationship that Mino Raiola, his agent, has with other players serving at Manchester United, there's no denying that he can lure the United hierarchy to pay attention and he can motivate Donnarumma to move as well.
He's been good for Italy and decent for Milan this year and one of his top qualities includes the command he has and his ability to punch the ball at the time of danger but concentration is a slightly weak area that he needs to focus on. There is talent in him and if United want him badly, they stand a good chance of getting him.