Man Utd boss Ferguson: Queiroz can be successor
"Thankfully, I don't have to make the decision," said Ferguson. "I have a great assistant in Carlos Queiroz, I think he will be a strong candidate."
But he added: "We have new owners now and I don't know how they look at the situation over in America.
"They have been great supporters of everything we have done but they may have their own ideas.
"The thing is I have not made my mind up when I'm retiring. It's a difficult one. It's not going to be an easy decision.
"The important thing is to leave a good team. The present team is very, very good but they will get better."
The former Aberdeen boss had planned to retire five years ago but changed his mind with the help of wife Cathy.
Ferguson, who was speaking to an audience at the Citizens Theatre in his home city of Glasgow, said: "I had won the European Cup, I wanted to leave a good team.
"But it's difficult when you get to that stage and you have been there that long, when you choose the moment to retire.
"One New Year's Day with the family we all went for lunch and I was dozing on the couch when the boss came in and kicked my feet and said 'you're not retiring'.
"The three sons were sitting behind her and what could I do?"