I think if we are considering all sports then you have to consider Detroit also, which has a pretty large market. But I agree with your list for the most part if that is the top 5. I would replace St. Louis with Philly though.
I wouldn't. 10,000 losses does not a following make. Detroit wasn't on my list because outside Detroit metro, who gives a shit about the Lions, Tigers, or Pistons? All they've had going for them for the last 30 years is the Red Wings, and shit, you can't even throw octopus on the ice anymore. Considering the success of the Rams and Cards is what made me give the nod to St. Louis, not to mention the fact that their sports history is nearly as long as anyone's. The only thing that really makes it kind of "mushy" is the fact that St. Louis hasn't had a pro basketball franchise since the Spirits of the old ABA.
Consequently, I had to really decide if Dallas perhaps didn't belong in there, given the immense popularity of the Cowboys, coupled with the success of the Stars since they moved from Minnesota, the Rangers, and Mavericks under Cuban. But all in all, Dallas is still all about the Cowboys, and just the Cowboys.