The San Antonio Spurs are operating under the premise that Tim Duncan will be returning in 2015-16 for a 19th NBA season, according to league sources. Although Duncan and fellow Spurs mainstay Manu Ginobili have yet to make a formal declaration about their plans for next season, sources told ESPN.com that the Spurs are optimistic about re-signing both at salaries that will also allow them to re-sign prized restricted free agent Kawhi Leonard this summer as well as pursue top-tier free agent LaMarcus Aldridge. As ESPN.com reported last month and again this week, San Antonio sits atop Aldridge's list of preferred destinations should, as widely expected, he choose to leave the Portland Trail Blazers this summer. A source told ESPN The Magazine's Chris Broussard earlier this week that Aldridge is "99.9 percent gone" from the Blazers. ESPN.com also reported this week that the Los Angeles Lakers have moved past the Dallas Mavericks in terms of potential landing spots for Aldridge, who played his high school ball in Dallas before starring collegiately closer to San Antonio at the University of Texas in Austin. It has been widely assumed in league circles that the Spurs would be forced to try to trade veteran forward Tiago Splitter to help create the needed salary-cap flexibility to handle the max deals San Antonio has earmarked for Leonard and the likes of Aldridge or Memphis' Marc Gasol and still have room to accommodate Duncan and Ginobili at reduced salaries if the latter two chose to play on. But sources told ESPN.com that the Spurs actually rebuffed trade interest from teams hoping to pry Splitter away in conjunction with Thursday's NBA draft, raising the possibility that Splitter might also stick around. - See more at: http://espn.go.com/nba/story/_/id/1...hink-tim-duncan-likely-return-19th-nba-season