But Lions wing Williams hopes the man who coached the Lions pack on their 2009 tour to South Africa could be persuaded to stay on - and spearhead their World Cup bid in 2015.
"I'd love Warren to stay on beyond the World Cup," said Williams.
"I've played some of my best rugby under Warren and I have enjoyed my time working with him - I've learnt a lot.
"We have become friends so, on a personal and selfish level, I'd like him to stay.
"And as for Wales going forward, I believe he's the right man for the job. I hope he does decide to stay but he's got his own mind and targets."
Williams proved to be the catalyst for Gatland on their way to a Grand Slam triumph in his first season in charge back in 2008.
The 33-year-old became Wales' record try-scorer, was named IRB World Player of the Year and also won a Test place with Britain and Ireland's elite a year later.
And Williams reckons his form on the Test arena is down to the responsibility placed on him by former Ireland and Wasps boss Gatland.
"Warren has given me a licence to play and I think I've come of age in the last couple of years," added Williams.
"The way he has got Wales playing certainly suits my style. We play an open and expansive game and we've a good structure too.
"When I play for Wales I do feel I have a big role where I don't have to be too structured myself and can get involved as and when I like.
"It's nice to have that job and I've almost become a leader. It brings out the best of me."
Williams missed the summer tour to New Zealand in order to cure a long-standing shoulder problem but should be fit for the start of the Ospreys' Magners League title defence at Ulster on Friday.
But he is also keen to add to his 73 Welsh caps and bow out at the highest level by playing in his third World Cup.
"It's a massive season for me. I'm expecting big things from myself and I want to get my Wales place back.
"There is a lot of competition for my spot and Leigh Halfpenny and Tom Prydie performed well in the summer.
"But I want to play in the World Cup next year as that will possibly be my last Wales game."