The New York Daily News reports that the current plan is for Stern to inform the owners that he will step down after two more seasons, presumably after the 2013-14 season. From the Daily News:
Insiders say that David Stern is planning to tell NBA owners at their April Board of Governors meeting that he’s good for two more seasons, and that he’ll step down as commissioner then. “At one point, he had talked about doing it for one more season, but it looks now like two more,” said a league source. League suits say there probably won’t even be a search conducted to find a successor and that deputy commissioner Adam Silver is a lock to succeed Stern, with one source saying Stern’s lieutenant has the backing of almost 90% of the owners. All he needs is a simple majority.