Wan-Bissaka had a solid campaign for the Eagles last term and the 21-year-old is an extremely important member of Roy Hodgson's squad.
Although initially starting out as a squad player, the England U21 worldwide became a regular starter for the Premier League side in the 2018-19 season, making 39 appearances in all competitions.
Palace will need someone else to replace right-back Wan-Bissaka and Aarons has emerged as the flawless option following the season he has had in the Championship with Norwich City.
But Palace legend John Salako has told Wan-Bissaka to look at the likes of Alex Oxlade-Chamberlain and Wilfried Zaha before him who moved to big clubs too early in their career.
Premier League champions Man City are also interested in signing Aaron Wan-Bissaka but they are monitoring the situation closely.
United manager Ole Gunnar Solskjaer is targeting right-back Wan-Bissaka as part of his summer overhaul, but United have had an initial offer of £35 million plus £5m in add-ons turned down. But don't they already have one at the club?
Defender Ben Godfrey has been linked with a move to the Premier League, as has young full-back Jamal Lewis. The Ecuadorian star is mainly a winger but in the post-Ferguson era, he has been utilized in the right back position.
The Red Devils must bid higher if they want to land the 21-year-old.