When they re-signed, I suspected the plan was to play out their contracts, barring a significant injury or (further) precipitous decline. The former, you never know. The latter, I was confident they could hold off. Ginobili, despite his performance waning as the season has wore on, mostly has, but I think he'll follow Duncan's lead on this.
It pains me to say it, but more and more, it's looking like this is the end, unless Duncan's knee injury isn't just wear and tear and he thinks he'll be able to somewhat bounce back next season. If not, I can't see him putting in all the work he has to throughout the year just to go through a full season of this. Not only that, but he's probably too prideful to do so.
The biggest takeaway, is that it appears the Spurs don't believe they can beat the Warriors in a series and the Warriors don't believe the Spurs can beat them in a series and when those two things are the case nothing else really matters.