Tim Duncan exercised his $6.4 million player option for next season but retirement remains an option.Duncan had ups and downs in 2015-16 in the regular season and playoffs but said he is still weighing whether to play one final season after helping the San Antonio Spurs win a franchise-best 67 games and tying an NBA record for going 40-1 at home this season.The Spurs were eliminated by the Oklahoma City Thunder on Thursday night in the second round of the playoffs.After a loss in Game 6 of the Western Conference semifinals, Spurs coach Gregg Popovich joked that Duncan and Manu Ginobili could go another five years. Duncan wasn't in a talking mood after that defeat but the introspective veteran will be 41 next season."I'll get to that after I get out of here and figure out life. That's it," said Duncan.Popovich feigned surprise when quizzed about Duncan's immediate future."Do you know something that I don't know? I just wanted to make that clear. Tim was playing really well. So we played him as much as we possibly could because he earned the minutes. He really did a good job," Popovich said.The 38-year-old Ginobili said he plans to take his time in making the decision about a possible return to the Spurs for a 15th season. His option for next season is worth $2.9 million."It's been an amazing run," said Ginobili last month. "We all enjoy playing with each other. I'm so proud of having played with those guys for so many years and winning so many games, and even playing with the new guys."If there's a reason why you always want to come back and keep being part of this, (it's) because of the amazing chemistry, the good times and the good people that you play with and spend time with. It's not always about winning a game or winning a championship. But you learn from losses, and it's important to enjoy every day. Being a part of this team, I'm very proud of it, even if sometimes it doesn't go our way."