McLaren parted ways with eight-time grand prix winner Daniel Ricciardo a year before his contract was due to expire to secure the services of Piastri, who won the Formula Renault Eurocup (2019), FIA F3 (2020) and F2 (2021) titles on his climb up the junior single-seater ladder.
While this season's McLaren MCL60 has been hamstrung by excessive drag and is sensitive to changing balance when facing low-grip conditions, Piastri was able to score his first F1 points with eighth place in his home race in Australia.
He was also classified 10th in the Azerbaijan sprint race despite suffering from a stomach bug.
Piastri's campaign has also been blighted by an electrical fault that forced him to retire from the Bahrain opener and a brake-by-wire failure last time out in Miami.
But McLaren Racing CEO Brown reckons he has already seen enough to declare Piastri an F1 champion of the future, so long as the Woking team can provide him with more competitive machinery.
Brown said: "We're very impressed with him. He's very focused. He's not really made any big mistakes. [Just the] typical exploring of the limits, so the odd lock of a wheel here and there.
"He's not been to all these [circuits used so far in 2023] so early indications are we've got a future world champion on our hands.
"We just have to work to give him a faster car now."
Similarly, Piastri has continually received a glowing report from new team principal Andrea Stella, while team-mate Lando Norris has implied he is more competitive than predecessor Ricciardo, saying: "[He's] been pushing me a little bit more than the past couple years".
Brown added that McLaren could not now devise a better drive line-up, saying: "Oscar has been impressive since we've had him in the car. He's very mature. He's very focused and he's very technical.
"The combination of Lando and Oscar, I couldn't think of a better combination of drivers…
"Oscar has done a fantastic job and he's trading lap times with Lando now and that's what you want."
