Silly discussion. Take a look at the Mavs salary commitments for next season.http://data.shamsports.com/content/pages/data/salaries/mavericks.jsp
Now, for the sake of argument, take away the qualifying offers to Collison and Roddy B, as well as the player option for OJ Mayo (which he'd be crazy to pick up). Now look again at their commitments.
Dallas will have huge cap space this summer, and Dirk. Not only do they need him to compete for a championship next year, but they need him to lure Dwight Howard and other FAs so they can compete for a championship next year.
He's there until at least the trade deadline in 2014, and likely for the rest of his career. End of discussion.