Exactly. This looks like a "one for the future" kind of signing. Someone they hope / expect to come good over the next couple of seasons. Not to say we won't see plenty of him as an impact sub, or starting in the early rounds of the cups; but I'm half-expecting us to sign Berahino for some reason (been suckered by the media and gossip!) and I'm guessing N'jie will be third-choice striker and back-up wing forward.
If we sign Berahino and N'jie, we would have three strikers all of whom are 22 years old. That's got to be the youngest strike-force in Premier League history, right?
Of course, N'jie is slightly younger than the other two (he won't be 22 until this weekend says Wikipedia) and doesn't have any experience in England. So he'll definitely be eased into the side while I imagine we'd dump Berahino in at the deep end.