Williams is targeting next year's Rugby Union World Cup with the All Blacks but his future beyond that is undecided.
The dual international turns 34 next August and is weighing up ending an illustrious career spanning Australia, New Zealand, France, Japan, rugby league, rugby union and boxing.
Williams became a pariah in the 13-man game after his walk-out on Canterbury in 2008 over a contract dispute.
He returned to play a leading role in the Sydney Roosters' 2013 NRL premiership victory, only to again return to union, where he won the 2015 World Cup and appeared in the 2016 Olympics.
He's eyeing his third World Cup next year but refuses to rule out a third stint in rugby league in 2020 and says opportunities to work with the Pacific community and in coaching will affect his decision.
"I'm 34 next year. I'm just happy doing what I love doing," Williams told Fox Sports.
"I really want to affect my Pasifika people. With that comes responsibility.
"I need more knowledge in that field, which I'm doing - I'm doing for my coaching papers.
"God willing I make it through next year and I make that World Cup side.
"Then after that, I have to keep the wife happy and then if I do play on, it'll have to be at a place where I can still have a voice."
Williams returned to the Roosters for two years in 2013-14 after a handshake agreement with Roosters chairman Nick Politis, which was struck following his first exit from the NRL.
In the past few years, there have been rumours Williams will end his career with the Tri-Colours.
He refused to give anything away about his future on Sunday but said he regretted the way he turned his back on the Bulldogs, the club that gave him a start as a teenager.
"I still stand by my decision to leave. Though as a young fella you're a bit rash and you do things you probably regret," Williams said.
"I'm no different. I'm human, I make mistakes.
"When it came to that decision to leave, although things weren't going the right way off the field, I just felt like I was backed into a corner and that was all I could do.
"Looking back now, if I was a lot more confident in myself as a man, I probably could have gone and spoken to the administration and told them, 'Look, I'm going to leave if you don't do what you guys promised me'."