Simon is reported to be set to reprise his place on the ITV1 show, following a dip in the ratings.
"I have enjoyed this series more than last year, but the show feels like it has been going on for a year this time. If this is my last year, I've had a lot of fun and enjoyed every minute."
The Take That star, 41, spoke at London's Royal Albert Hall, before he went on stage for his solo show.
Gary and Simon are said to have had their disagreements since a biography, which was written with The X Factor boss' approval, said Gary was "wooden".