Emmitt Smith toiled in Tempe, wearing an Arizona Cardinals uniform. Mike Modano skated, however briefly, with the rival Detroit Red Wings. Rolando Blackman's number hangs in the rafters of the AAC but he closed his NBA career as a New York Knick.
So if Dirk Nowitzki were to reverse field, opt out of his contract this summer and test the free-agency waters, it wouldn't be the end of the world -- just the end of a franchise as Mavs' fans have come to know and appreciate it for nearly two decades.
I'm not waffling on what I wrote just a few days ago, that I (and everyone else) expect Nowitzki to play out his career in Dallas.