England's wicketkeeper-batsman - speaking to Sky Sports' Ian Ward in an interview you can see during coverage of the T20 Tri-Series game against New Zealand from 5.30am on Sky Sports Cricket on Tuesday - believes the Test and ODI games could be phased out "soon or in 15 to 20 years".
However, Buttler, who played the last of his 18 Tests to date against India in December 2016, says the five-day arena remains the "pinnacle" and that he would be "sad" if it was jettisoned.
"I feel cricket could become a one-format game in the future - whether that's soon or in 15 to 20 years," said Buttler, who talks more about the T20 Tri-Series in his latest Sky Sports column.
"Test cricket is still, for me, the pinnacle of cricket but T20 fills out stadiums and is easy to keep up with and follow.
"Everyone wants things faster these days and things evolve so maybe Twenty20 could have a monopoly on cricket.
"We all love the history of Test cricket - you will never have situations thrown up in T20 that Test cricket can do to you and you will never be tested as a player as you would in Test cricket.
"It's a complete test of everything and it would be sad (if it went), but as a product T20 is going from strength to strength.
"Hopefully the administrators can find a way of making the Test game more popular - it's awesome and I'd love to be playing in it.
"[Not making the Ashes squad] was a wake-up call that I have slipped down the ladder in red-ball cricket and white-ball cricket is obviously my strength.
"I thought if I'm serious about playing red-ball cricket I could give up the white-ball stuff for two years and spend winters playing red ball, but I feel like there are too many opportunities to go down that route."
Hear more from Buttler in the video at the top of the page - and then watch England's tour of New Zealand in full live on Sky Sports Cricket, starting with Tuesday's T20 international in Wellington from 5.30am.