Ok I will go deeper. Paup is "forgotten" because he is already in the system but not because anyone doubts his potential or doubts how much he will improve, or doubts he will be the next Cole Conrad.
He is "forgotten" because he has already said yes. It's time to move on to the next class of recruits. Now he has to show it on the field.
Fans are always looking to replace what's here with something better. I'd imagine the coaches are doing the same thing.
Edit - I can hope Paup never plays a down at Nebraska because the players recruited in his class and after him are just simply better. That isn't meant to be a slight on the kid. I can hope the same about Butler, Dismuke, or Anderson.