The G-League is aggressively expanding...they added 3 new teams in '16-17, 4 new teams in '17-18, and 1 new team in '18-19 (Wizards). A grand total of 27 G-league teams this coming season.
27 teams, each with a roster of around 12-14 guys (depending on flex and 2-way contracts), is around 350-400 players. I'd assume there would be a spot for Cook somewhere in there. Most players don't stick in the G-league for too long. They either chase the money in Europe, get called up to the NBA, or wash out of the program.