The 35-year-old, who has been ruled out for the rest of the campaign with a knee injury, will leave Fulham when his contract expires this summer.
Duff now admits that he is keen to experience "a different way of life" before he decides to hang up his boots.
"I'm up at the end of the season. The club haven't spoken to me and I haven't spoken to the club, but we don't need to speak - I'll be leaving Fulham," he told the Irish Times.
"I've had a few whispers from here and there, but I'm just trying to get this [knee] right first.
"I've looked at the Australia or America thing for a bit - it would be a different way of life, a different league. I think life's too short just to be stuck in the rat race, if that's the right phrase, over here so I'd maybe like to taste something new before I go back home."
Duff joined Fulham from Newcastle United in 2009.