I saw an interview on ESPN with him and he said something along the lines of coming back to stop Karl Malone from getting a championship... I couldn't tell if he was joking or not... But I think there might be a half-truth in it.
I doubt he'll be of much use to any team. He's been out of the NBA for 3 years living it up, was a liability on offense and his biggest contribution was his energy and fight for every board. I'm sure his age has caught up with him and he won't have the energy he used to have.