Ryan Giggs believes it "could be 15, 20 years" before Manchester United win the Premier League title again.
Sir Alex Ferguson delivered a 20th league crown to Old Trafford in his final season at United in 2012-13, before passing the torch to fellow Scotsman David Moyes.
Unfortunately, the ex-Everton boss only lasted 10 months in the hot seat before being replaced by Giggs on an interim basis, and the Red Devils subsequently fell to their lowest ever Premier League finish.
Louis van Gaal was the next man charged with bringing back the glory days, but he was sacked after two seasons having failed to guide the club to a higher finish than fourth, with an FA Cup triumph seen as little more than a consolation prize.
United then turned to three-time Premier League winner Jose Mourinho, who won the Community Shield, EFL Cup and Europa League in his first full year at the Theatre of Dreams.
The Portuguese went on guide the team to a second-place top-flight finish, but ended up suffering the same fate as Moyes and Van Gaal after a poor start to the 2018-19 campaign.
Ole Gunnar Solskjaer succeeded Mourinho in the hot seat, and has since set about restoring the identity which saw the Red Devils dominate English football under Ferguson.
The Norwegian is, however, still on the lookout for the first major trophy of his reign , with Liverpool now back on their perch after winning a first league title in 30 years last season.
Giggs fears United might end up enduring a similarly long wait for a return to the top, having seen their arch-rivals struggle to find a winning formula until Jurgen Klopp's arrival at Anfield in 2015.
"Yes, 100 per cent," the treble winner told the Greatest Game Podcast when asked if he is concerned that the Red Devils' Premier League drought could potentially continue for decades.
"It could be 15, 20 years before you know it, especially if [Jurgen] Klopp and [Pep] Guardiola stick around.
"They have got the resources and the players so we have Liverpool to look at, where the last time when they won it in 1990. They thought 'we'll win it again soon.'
"Even Klopp, it took four-and-a-half years for him to win it - it takes a long time.
"You have to think about what Klopp did.
"He improved the team every season or won a trophy like the Champions League and then you saw the improvement so the pressure was off a little bit.
"Every manager and signing [for United] is seen as that 'he will win us the league' and it's not like that."