The 69-year-old is the longest-serving manager in England and celebrates 25 years at Old Trafford next month. Last season, he led the Red Devils to a record-breaking 19th league title, but has no intentions of retiring yet.
"I've got three or four years left," the Scot told reporters. "I feel good.
"When I do leave, I will leave in place a strong young team that will continue to succeed for my successor."
Ferguson, who is the league's oldest manager, will turn 70 on New Year's Eve.