The NBA appears to be attempting to start a farm system by revamping the D league to the G League (Yes it stands for Gatorade) and changing its requirements. Two roster spots will be allowed to float between the new G League and the NBA as well as letting players enter at 18. Although Silver does say the league prefers players enter college as opposed to the G League. This will impact the college game; only time will tell how much.
https://www.usatoday.com/story/sports/nba/2017/06/20/nba-official-d-leag...
Players can enter the G League at 18, and the NBA said it plans to explore the idea of high school players going directly into the G League, though it still prefers the college route to the NBA.
“As I said, when we now have 20 members of a 60-person two round draft coming directly from one year of college, I think from a training standpoint we really got to rethink this process,” Silver said.