Brook was omitted from the preliminary party to travel to India in the autumn, nudged out of contention by Test skipper Ben Stokes being selected as a specialist batter after reversing his ODI retirement.
England have until September 28 to finalise their 15-strong group and Brook delivered a jaw-dropping reminder of his capabilities with a 41-ball ton for Northern Superchargers in The Hundred this week.
While Buttler is standing by last week’s decision, he suggested he has not entirely discounted Brook, who has become an automatic pick in the full-strength Test and T20 sides, from his thoughts.
Speaking ahead of Manchester Originals’ men’s eliminator against Southern Brave, Buttler said: “There’s still a long time before everyone’s meant to get on the plane so we’ll wait and see what happens.
“We all know Harry’s a fantastic player and we saw what he can do the other night, it’s not like it’s a surprise, we know what a brilliant player he is.
“He’s just the unfortunate one at the moment to not be in that squad. Ben Stokes coming back and being available just as a batter changes the dynamic a little bit.
“Ben’s a fantastic player to be able to welcome back. It’s a really tough selection, there have been players performing really well over a period of time and that’s where we are at the minute.”
After the conclusion of the group stages of The Hundred, Brook, whose Superchargers side were unable to reach the knockout rounds, sits second in the run-scoring charts, behind only Buttler.
The Originals captain’s 298 runs at an average of 42.57 and strike-rate of 143.26 has underpinned their success, where they will be hoping to go one better after losing last year’s final.