Not really a football fan, but it's too bad AT&T Stadium is closer to Fort Worth than Dallas. Because of that, it will be difficult for Fort Worth to ever attract a football team (thus get out of Dallas' shadow).
With the current alignment of teams, it is very unlikely that the NFL wil or wants to expand. And I think that any team owner can veto relocation of another team.
Yes, I suppose the NFL is tribalistic in a modern sort of way. But these comments are correct and no one realistically believes the NFL will allow a "Fort Worth Rounders" (my pet tag for a local sports team) to compete only 30 miles from the Cowboys. Why not when the Raiders compete only 15 miles or so from the 49ers?
BUT the point should be made that, in this mass media age, a U.S. city appears to enjoy national notoriety and identity if it has a popular sports franchise. Certainly population is the not the controlling factor here. Consider Green Bay, one-third the size of Arlington, Texas, yet if you asked a New Yorker where the Packers play football they'd say Green Bay. By the same token, if you ask a New Yorker where the Cats play, they'd probably say the musical is currently playing on Broadway.
So, we can attract other major sports franchise possibilities...baskeball, ice hockey, maybe soccer. At least Fort Worth's got the Colonial as part of the PGA circuit and the TMS for national NASCAR racing.