Now or Never for the Boston Celtics?

For the last three years the Boston Celtics have been major contenders in the NBA playoffs, ever since they made that huge trade for Garnett to put the peices in place for a championship run in 08'. Throughout the 2010 regular season you could see all of the wear and tear between Allen, Garnett, and Peirce as they all are approaching the twilight years of their careers and I'm just wondering if they will have any gas in the tank for the future or will they just burn out like the Spurs are doing with Duncan, Ginobl, and Parker.