It is disappointing to see him leave and it appears to be a trend especially with centre forwards (Tyreece Campbell and Bobby Duncan left at the same age). Clubs always chase goalscorers and therefore they will be in more demand.
United are attempting to push forward with their Academy they will see this as a coup.
By the way, the Moulden comparison does have some relevance. Both him and McNeill were born in early Sept giving them a tremendous advantage over their peers and helping them accumulate goals. Especially as both boys matured early also.
I would suspect Charlie will still do fine but maybe not quite to the level they expect.
For me if Bynoe-Gittins leaves, this will be the biggest loss. I rate him as a much better prospect than Delap. If he goes to Dortmund, if suspect City will be pushing for specific ongoing transfer clauses!