Wan-Bissaka is never worth £60 million.
It's hard to know really. He's absolutely miles better than Walker was at 21 IMO, and he has all the necessary attributes - pace, ability on the ball, tackling - to be a top full back.
I don't think we should be spending 50-60m on players like him, but if a team like United was being run competently, he could be a sound investment - the kind of player who could hit that top level in a couple of seasons.
If we were on the up again like we were circa 2010, I think he'd be a good buy.