His G/A this season is heavily boosted by his Carabao goal involvments vs Barnsley and Leicester. That's 3 goals and 3 assists in 2 dead rubber games vs weak opposition. If you take those away, he's not really had exceptional output in either of his 3 senior seasons so far, and he'd be on 5 goals and 2 assists halfway through the season, which aligns closely with how he's produced in his previous two seasons...but that's totally fine, as he is a prospect like you said, and I'm not debating that.
However, considering him one of the best young talents in the world, just because of his age and the fact that he's playing regularly for one of the biggest clubs in the world, is putting blind faith in him becoming a world beater IMO. There's really nothing about his overall skillset and profile for me that indicates he's going to become anything more than a solid Premier League level winger with good work-rate and acceptable output.
If I'm correct in my assessment, is this player with not an exceptionally high ceiling worth more than 55-60m at best? We would be getting a peak, or close to peak potential sort of fee for him, unless you think he can turn into a 100 million player, which is unlikely IMO.