Nowitzki, 34, missed the season's first 27 games due to a knee injury and says he has been "brutal", only averaging 16.0 points and 6.2 rebounds while shooting 43.5 percent from the floor this season.
"When my [current] contract's up, I'm 36 and I'll definitely sign a couple more years. It's still fun, but I don't know if I'll play until 40. But when I'm 36, definitely sign one more deal, maybe two or three years," Nowitzki said to ESPN.com. "Obviously, if you're tall and you can shoot like Sam Perkins and those guys, they can play until the end of their 30s if you're out there and you're spreading the floor. Obviously, in five, six years, if I make it that long, I'm not going to like take every shot in the fourth quarter, but I'm going to be out there spacing the floor and be smart if I make it that long."