It has been like the end of an era at United throughout 2011 so far.
Gary Neville, Paul Scholes and Edwin van der Sar have all announced their retirements, whilst long-serving duo Wes Brown and John O'Shea left this week for Sunderland.
As ever though, Sir Alex Ferguson is re-energising his team.
Vast experience remains in the form of Ryan Giggs, now into his 21st year at Old Trafford, Rio Ferdinand, who is about to start his 10th and Wayne Rooney, who has seven years' service behind him despite only being 25.
And it is easy to see Smalling still being around in another decade too, after pocketing a lucrative new contract as reward for an outstanding debut season following his arrival from Fulham 12 months ago.
"This is a great club and in the short time I have been here I have already achieved more than I could have ever expected to," said the 21-year-old Londoner.
"I am looking forward to a long and successful career at Manchester United."
Sir Alex Ferguson is of the same opinion about a player who far exceeded expectations during his debut United campaign, considering he had been playing in the non-league for Maidstone less than two years before joining the Premier League champions.
"Chris has been outstanding since joining us from Fulham last year," said Ferguson.
"He is an extremely talented young defender. He is quick, strong and reads the game well. He is a great asset to the team."
Ferguson has brought in more youth this summer in the form of Spain Under-21 keeper David de Gea and Blackburn defender Phil Jones, aged 20 and 19 respectively.
It means United have a talented trio who could be around for a long time and, including the likes of Ravel Morrison and Paul Pogba, two of the more notable members of last season's FA Youth Cup-winning team, could form their own version of the famed 'Class of 92'.
Not that Neville views it as particularly extraordinary at a club like United.
Indeed, the former England star denies the days of one-club men like himself are drawing to a close.
"It is very easy for clubs like ourselves, Liverpool, Chelsea and Arsenal to keep players for their whole career," he told Key103.
"Why would players, who have grown up in the area and been part of successful teams, want to leave?
"AC Milan, Bayern Munich and Juventus have all kept players for long periods of time.
"We have been at the right club, within 20 minutes of our home and the manager never wanted to get rid of us.
"For us it is easy to say we are loyal and one-club men. We were at the right place at the right time and delivered the right level of performance.
"Rio Ferdinand supported West Ham as a kid. He is not a mercenary for wanting to move to Leeds and then Manchester United. It is the same with Wayne Rooney.
"They are trying to get to the pinnacle of the game."