I don't know why so many people think JHS is gone. He is a freshman, and He is having a great year. But He is 19 Years old, thin, and doesn't have the physical maturity or body strength to compete consistently with older Players over an 81 Game Schedule. Everybody thinks being in the NBA is wonderful because You get to play or practice all the time. However, when Teams are on Road Trips, their Practice Schedules are disrupted.
They may not practice at the same time each day. They don't have access to the same type of facilities they have at Home. Based upon availability, they may be practicing in a Junior College or High school Gym. Depending upon travel arrangements and timing a Road Practice may be a walk through to game Plan for the next opponent. If You are a Young Player toward the end of the Bench it may be difficult to keep Your game up and improve.
If You stay in College, You have the opportunity to grow another Year and become more physically mature. You know You will play 3 5-40 games, practice consistently, and have unlimited access to a practice facility.
I know, this ignores the Economics and Money. If You stay another Year and improve, Your draft stock may go up. and You may move into the first round or higher in the first round and make more money in the long run.