Whilst im not the biggest williams fan and think he is short of the quality needed to be a top 4 player, I do think he does have a pretty decent base skill set in terms of a good touch, decent crossing, passing, dribbling etc. So whilst I think its a hugeeee long shot, if you tell me in 5 years time that he will be playing the cancelo role for a top 4 team I wouldn't be that shocked.
Its just so hard to tell sometimes with players. Dalot for example was absolutely dreadful 1 on 1 defending, but since Ralf has given him a run its actually been pretty good.