Australia spin great Warne thinks the Yorkshire star could dominate the global game with the bat and feels Buttler would make a "very, very good" Test captain.
Warne worked with Buttler in his role as mentor for IPL outfit Rajasthan Royals, and is convinced the Lancashire keeper has credible Test leadership skills.
"I've worked with Jos a bit this year, and I think he's someone who would make an excellent captain," Warne said of Buttler. "I really enjoyed working with him, I'd like to think I helped him out a little bit.
"I really enjoyed his company, and talking the game of cricket with him. He would be a very, very good England captain.
"I think Joe Root is England's best player. But he'll be disappointed with his conversion rate when it comes to hundreds. He'd love to have more hundreds to be able to be spoken about in the same sentences as Virat Kohli and Steve Smith.
"I like Joe Root, he has a good manner about himself. He's a gentleman. Maybe England could think about their best player having the shackles off, not having the responsibility of captaincy, and give it to someone like Jos Buttler.
"Jos could play with his freedom and captain the side, and Joe could just concentrate on his cricket. If he totally 100 per cent concentrates on his cricket, his batting and nothing else, then maybe we might see Joe Root become the best batsman in the world. He's got the talent to do it."
Warne is busy promoting his autobiography 'No Spin', where he charts his 708-wicket Test career in typically candid fashion.
The 49-year-old believes Australia have lost the "fear factor" ever since England won the 2005 Ashes, but he also thinks next summer's series in England could be very delicately balanced.
Disgraced pair Steve Smith and David Warner will be back from their ball-tampering suspensions in time for that series and Warne expects both men to regain pivotal roles in Australia's set-up.
"I think they need to earn the respect back," Warne said of Smith and Warner. "I don't understand how it gets to that stage where you decide to take sandpaper into the dressing room and then use it on the ball.
"It's going to be tough for them at first. Forgiveness takes time, but there's nothing like making a couple of hundreds in a row and people thinking, 'Oh, we've missed this guy'. They have to be aware that they're in for a bit of a hostile time around the world until they've earned the respect back.
"By the time Smith and Warner are ready, Australia will be pleading to have them back, they are two of the top five best batsmen in the world. Australia desperately need them.
"I think Australia will give England a real run for their money next year. I don't think England have feared Australia since they won the series in 2005, which they deserved to as the better side. Since then England realised Australia can be beaten.
"Australia haven't really got too many X-factor players. But I don't think Australia really fear England too much now either, aside from Jimmy Anderson bowling with the Dukes ball."
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