NBA teams are assumed to hold a player's draft rights up until the moment they sign. For the most part, that's the case. Players good enough to get drafted usually are good enough to sign elsewhere in the world if they know an NBA team won't give them money, or will cut them immediately. Chu Chu Maduabum keeps picking up work, to this day. Arsalan Kazemi played in Iran. Marshall Henderson played professional basketball in Iraq!
If you're a basketball player with even modest renown, you can find work. Which is why the assumption I mentioned above is made.