The teams that seem to struggle the most financially/attendance:
Florida: 3 playoff appearances in the last 20 seasons, zero series wins
Arizona: 6 straight seasons out of the playoffs, only three playoff appearances in the last 15 seasons, and only two series wins in franchise history.
Columbus: 4 playoff series in 17 seasons, zero series wins.
Carolina: 9 straight seasons with no playoffs, 5 playoff appearances in 20 seasons (granted they did win a SC)
Atlanta (when they existed): Missed playoffs for 10 out of 11 seasons, no playoff series wins
You compare that to the southern teams that seem to do pretty well financially:
TB: 9 playoff appearances in the last 15 seasons, including three Conference Finals, at minimum two Finals appearances (might make it this year), and one SC win.
Nashville: 11 playoff appearances in last 14 seasons, one SC Finals appearance
St. Louis: ~50 year old franchise (time to build a fanbase), 7 playoff appearances in last 10 seasons
Dallas: this team has struggled the last ~10 years (only 2 playoff appearances), but they were in the playoffs for 12 of the previous 14 seasons, including a SC win.
So is it bad markets? Or just markets that have never really had a chance to grow a brand, because they've generally had crappy teams for the vast majority of their history? Most of them have missed the playoffs for 75%+ of their history, and several have zero playoff series wins in their history. It's not like they'd be great hockey markets with good teams, but it's reasonable to say they'd be better off financially if they'd had better teams.