This is an excerpt from a story published by Argentine sports paper Ole about Manu Ginobili (here's the link to the original in Spanish):

Manu 2016 At 35 (Ginobili) understands the game better than ever and he still dunks, from time to time, but he knows the end of his career is nearing. "I want to play two more years, minimum," Ginobili said when asked about his future. His contract expires after this season and then it's time to start the negotiations. He's the highest paid Spur this season, with Parker ranking second and Duncan in a surprising fourth place after Stephen Jackson. How much could Ginobili get in the open market as a free agent? The Spurs' front office doesn't even want to think about that and is trying to get ahead of the game by planning to offer a three year deal. It looks like number 20 will wear Silver and Black until 2016...

Now, first of all it's important to mention that there is no source credited with the information so you should take it with a grain of salt. Ole is also better known for their soccer coverage, with basketball being almost an afterthought. That being said, Ole usually has connections with inside sources, including managers and a lot of times the players themselves and the language the writer uses seems to suggest that he does have a source in this particular case.

The biggest cause for skepticism would be that a three year contract wouldn't coincide with Tony Parker and Tim Duncan's deals, which expire in 2015. Parker's contract is only partially guaranteed that year and Duncan has a player option. Unless something catastrophic happens, the Spurs will likely keep Parker and if the team is contending, Duncan will likely pick up his player option, too. In that case, offering Ginobili a three year deal with only two years fully guaranteed would make sense, as he could be released in 2016 if the team wants to rebuild.

If new information surfaces, we'll keep you posted.