I think Delap can make it at the top.
But, atleast for me, I have learned to be careful in categorizing youth potential. Players like Sancho and Foden had what I call "obvious" potential, everything they showed at youth level showed they would make it at the top, and more specifically, they didn't rely on any physical strength over peers who may not have developed.
Nmecha and Solanke are 2 immediate examples I think of who look amazing at youth level, with great numbers, but then you start to think is it because they are physically superior? Now you see them at adult level and think that maybe that was a factor in their performances.
Haven't seen Delap play THAT much, but he is a physical beast. More importantly it will be interesting to know whether he can develop faster so that he isn't scoring goals due to physicality because he will lose that quicker against full adults. I think he does have that potential (he did play 1 senior game for us where he scored), but I am just not immediate in my view of his potential like Foden and Sancho.