According to his coach he's at 60% of his potential. Kid is 19, think he can still improve although maybe not that much imo.
He's 20, and his coach is supposed to hype him up.
The area where he will struggle (compared to GOAT tiers) is mental strength. To me, he was kind of in overdrive first two sets.
The only GOAT tier with suspect mental strength is Federer and he was still GOAT tier because his natural ability was off the charts great. Djokovic, Nadal, Laver, Sampras etc. were all mental monsters.
I'm thinking he is a Becker/Andy Murray(prime)/Edberg/Wilander tier player.