"The thing is I have not made my mind up when I'm retiring," Ferguson said.
"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."
"Thankfully I don't have to make the decision," Ferguson continued.
"I have a great assistant in Carlos Queiroz, I think he will be a strong candidate.
"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."
He also talked of other Premiership managers who have impressed him.
"Pardew at Charlton has got something about him, he is a good young manager," he said.
"Roy Keane has a good chance, he has something about him.
"Of the older ones, Sam Allardyce is a very influential manager."