I'm going by Wikipedia for better or worse:Are you sure about the scholarships? I thought that any GA has a pool of money sitting there for them to go back and get their degree at any future date - that was the model when Nike had the P-40 project going.
Entering into the program automatically classifies a player as professional, and thus disqualifies them from playing college soccer. As a result, Generation Adidas players are also guaranteed scholarships to continue their college education should their professional career not pan out. - [my emphasis
https://en.wikipedia.org/wiki/Generation_Adidas
OTOH this oldish source cited in Wikipedia says any GA player can use it but they have 10 years:
https://ussoccerplayers.com/2010/01/mccabe-explains-generation-adidas.html
I guess as a practical matter the ones most likely to use it are the ones who don't last several years, but any of them are eligible.