Ferguson will remain at the club as a director and ambassador, as Sir Matt Busby did when he stepped down as United boss following a glittering 24-year spell in charge. Busby's successors, Wilf McGuinness and Frank O'Farrell, both struggled while the former manager maintained a presence at the club - but Charlton insists Ferguson will not meddle.
"Alex Ferguson doesn't work like that. He won't interfere," said Charlton, one of the Busby Babes, who made 758 appearances for the club. "He is famed for his decision making and this will be just another decision."
David Moyes has been installed as the bookmakers' favourite to take the reins, while Jose Mourinho has also been touted as a potential successor.
Having dominated the landscape of British football for so long, United fans will no doubt fear a decline, but Charlton is optimistic about the club's future.
"There's no problem," said Charlton at the launch for the Royal Mail's Football Heroes Special Stamps. "Why should we not have anyone who we think is capable of doing it, and doing it with a bit of a smile?
"There will be (another manager like him). But I can't tell you who it is or who it may be. We have to get a new manager. It's actually quite exciting. In a way I've always dreaded this day. There's been a torment in my mind about this happening, but he's not going away, he'll be staying on as a director."
Charlton was one of the four men who appointed Ferguson way back in 1986 following the Scot's success at Aberdeen, where he broke Rangers and Celtic's monopoly of the Scottish game by winning three titles. He has since gone on to develop a close personal friendship with Ferguson.
Ferguson discussed retirement with England's record goal scorer on several occasions over the last few years.
"I have known for about three or four years (that he was going to quit), but he has changed his mind a couple of times," Charlton added. "City winning the title gave him a new challenge. Now I think he thinks he deserves to have a break. There's so much pressure on the position. It's very tough."
- Sports & Recreation
- Alex Ferguson
- Sir Matt Busby