He’s a very good player who could become great IMO.
He’s got that ability to keep the ball and find space with the ball that the elite level playmakers have. The likes of Kaka, David Silva, Iniesta and Ozil (in his prime) could all take the ball under pressure and glide with the ball. Grealish has that ability.
Unfortunately for him that’s where the comparisons end because his end product is nowhere near the top level, never mind elite.
In a better side though I wouldnt be surprised if he turned out to be a top class player.