Popovich is under contract for four more seasons but told USA Today's Sam Amick in February that he is unlikely to remain with the team for the length of the contract.
"No matter how [the season] ends, I think Timmy is going to look at [retirement] again," Popovich also told Amick. "And if you ask me, my guess is that he'll go for another one because he has been so consistent this season."
Duncan and Ginobili will become unrestricted free agents this summer.
Duncan, who turned 39 last week, has played for the Spurs since they selected him with the first pick in the 1997 draft. He is a 15-time All-Star and has won five championships with San Antonio, taking home Finals MVP honors three times.
Ginobili turns 38 in July and has played for the Spurs since 2002. He said in an interview with an Argentine newspaper last month that he is unlikely to play past 2016.
- Dan Gartland