As Mavericks GM Donnie Nelson pointed out in an interview with the Fort-Worth Star Telegram, Dirk is still two-three years younger than Tim Duncan and Kevin Garnett, both coming off deep post-season runs:
"Dirk, with his size and versatility, he's a thinker and he's a shooter, he's the kind of guy that can age very well," Nelson said.
Size and shooting ability are the two features that correlate the most with career longevity, for obvious reasons. Players don't get smaller in their late 30's and they don't forget how to shoot jumpers.
But while Dirk is a more dangerous offensive threat than Duncan and Garnett, both offer much more on the defensive end. Of course, the Mavericks had another 7'0 with Duncan's ability to hold position on the low block and Garnett's ability to contain penetration and play above the rim.
And if Dallas can find another player like Tyson Chandler, they'll be back where they were two years ago. Oops.