The report stated the roster would be made up of NBA D-League players, and another possibility was "recruiting Americans who are playing abroad in selected leagues that will consent to releasing players for qualifying windows."
Stein noted that NBA stars would comprise the roster for events like the World Cup and Olympics, "but the players entrusted to secure qualification for those events have to come from elsewhere because the NBA does not intend to release its players—of any nationality—for the in-season World Cup qualifying windows that begin later this year."
Because the qualifying tournaments will no longer be held strictly in the summer, they'll overlap with the NBA regular season. Not surprisingly, teams and the league weren't willing to part with their players, though they were willing to allow NBA D-Leaguers to play in the qualifying tournaments.
With new USA Basketball head coach Gregg Popovich also affected by the format changes, Stein reported that the "USAB has considered employing multiple head coaches during the various qualifying periods for the fresh rosters that will be selected for each of the six two-game qualifying sets to come."
For the time being, however, Stein reported that USA Basketball is expected to hire a non-NBA coach to handle the 12 qualifying games.
FIBA will hold six two-game qualifying periods between Nov. 2017 and Feb. 2019. Alongside automatic qualifier and host China, 31 countries will qualify for 2019's FIBA World Cup.