Right, which they can do, if Duncan only intends to play one more season
However they end up doing it, if Aldridge signs and Green re-signs, I'm confident that Duncan and Ginobili would work with the organization.
My only concerns this off season are: 1) Signing Aldridge, 2) Re-signing Green, 3) Ginobili returning. If those three things come to fruition, the top eight would be: Duncan, Aldridge, Leonard, Green, Parker, Ginobili, one of Splitter/Diaw and one of Mills/Joseph. The depth would take a hit, but the tradeoff on the top end would be more than worth it.