The trouble is any striker aiming to play for a CL team needs to be amongst the best of his generation. Nketiah is good but not at that level, moreover if we're playing with 1 striker then he's got even less of a chance to learn under the shadow of someone else. He does seem to be able to apply himself to the game more than Nelson and Willock which is a valuable trait.
I can see him going a similar route to Tammy Abraham, even though they're different kind of players.