Originally Posted by Caveat Emperor
The other league that springs instantly to mind with that, though, is the defunct IHL.
They tried to go big by doubling up on some major NHL markets (Chicago, Detroit, Los Angeles) and other cities that were larger but lacked hockey (Cincinnati, Cleveland, Kansas City, Milwaukee, Houston, Orlando, Salt Lake City, Las Vegas, Indianapolis). The league collapsed under it's own weight with costs skyrocketing and revenue never increasing to match.
Being a second-tier league is a tough balancing act -- keeping play quality strong while keeping costs down isn't easy.
IIRC, the IHL ticked off the NHL -- costing many IHL franchises their NHL affiliations/subsidization -- by moving into NHL cities. Even though, as far as I know, no such arrangement between MLS and NASL exists, the NASL, with the obvious exception of the Cosmos, would be wise to avoid existing MLS markets.
However, as another example to help prove my original point, following the NBA's expansion boom, CBA teams continuously failed miserably in Major markets, where opponents such as Yakima and Sioux Falls were tough sells there.