He praised Pope Benedict`s decision to step aside in 2013 as "courageous".
"Benedict should not be considered an exception, but an institution. Maybe he will be the only one for a long time, maybe he will not be the only one.
"But an institutional door has been opened," he told the Televisa channel.
Pope Francis has hinted in the past that he could retire, but said he was opposed to the idea of an age limit for leaders of the Catholic Church.
"To say that one is in charge up to 80 years, creates a sensation that the pontificate is at its end and that would not be a good thing," he added.
A papal conclave elected Pope Francis as Benedict XVI`s successor on 13 March 2013. He became the first Latin American to lead the Church.
During the interview he admitted he was "surprised" by the decision and had only carried a small suitcase to Rome, with the expectation he would return to Buenos Aires.
His simple style has won him praise from Catholics, as have his promises to reform the Curia - the Church`s internal government.
However, he said two years of his papacy had now passed and he felt it would not continue for very much longer.
"I do not know. But I feel that the Lord has placed me here for a short time, and nothing more," he added.
"But it is a feeling. I always leave the possibility open."
He told Televisa that he "did not mind being Pope", but missed the anonymity associated with life as a priest.
"The only thing I would like is to go out one day, without being recognised, and go to a pizzeria for a pizza."