He played Rafa Nadal, not only arguably the greatest player ever, but the player with THE greatest point-to-point concentration in tennis history, who continually plays his best at the biggest moments.
As for winning a Slam...maybe? But most likely not. He turns 25 in April, usually a player's prime, and is only 26th in the world. There is a huge difference between giving a top player a very close match in the middle of the tournament and actually winning a major.
Guys like Medvedev and Thiem are around that same age and well ahead of him in terms of their game and results, even ignoring the mental factor.