I think the only way such a thing would work is if you make sure to be everything TFP is not. For example, they are mostly (not wholly, but mostly) a big box store that caters to the everyday aquarist. Perhaps a boutique-type store that specializes in well-conditioned, quarantined rare fish/coral and hard-to-find, high end equipment with staff that go out of their way to cater to the customers and immaculate displays/holding tanks could thrive. Such a store could potentially attract customers from all the cities within 100 miles of it or more, but it would require staff with just the right type of personality, just the right advertising campaign, and the startup costs would be fairly high. Also, don't limit yourself to saltwater; the high-end planted tank market is booming.