Plus, it'll be hard for him to win statewide office in TN. As a Dem, it's tough enough, being black, he'll have a much bigger hurdle. (Did you know Carol Mosely-Braun was the only black Democrat Senator ever?)
So, his best hope is for a Senate retirement with a Dem governor -- or to get on the national ticket.
Regarding the race card: Bill Richardson's name is bandied about. I think a Hispanic without a Hispanic name will not excite that group very much. He could certainly swing AZ and NM and puts FL in further doubt.
But...he's a Clintonite and the Clintons cannot have any Democrat be president in 2004 except for Hillary.