We all know that in college sports that when a coach tells a prospect that he wants her to join the team, that doesn’t necessarily mean that he actually means it.
So when a coach tells the entire senior class that he wants them to stay, it also doesn’t necessarily mean that he means everyone..
For a lot of practical reasons, it doesn’t make a lot of sense for a coach to take back an entire senior class next year like Syracuse, let alone for the next 4 years.
Your list of schools where coaches have invited all of their seniors to return (USC, UNC, UVA, ND, PSU, Syracuse) is completely unsubstantiated and proves nothing. Except for Syracuse, almost no players from your list have even announced they will be coming back.
The fact that so many players have already transferred to other schools and no reserve players have announced they are staying next year is a stronger argument that many coaches are NOT inviting their entire senior class back. | 
