Nothing you just wrote is about the presence of teams in the markets. You look at other organizations to see what they're doing that works, absolutely. You don't just say "oh, they have all 3 leagues. Let's go there!"
OK, so here's another way of looking at the point I'm making here. Cleveland has NFL, MLB, NBA. The NHL really has no interest in going to that market. My city is often rumored for an MLB expansion team, but if Charlotte did get one it wouldn't make the NHL sit up and say "we should be there too!"
Here too, the opposite is also the case. Tampa has 3 of the big 4, including the NHL. St Louis. Pittsburgh. Nashville if they get an MLB team will be there also. None of these markets are ones the NBA seems to be interested in, though Tampa is because of the proximity of Orlando. Which cities are on their radar that already have NHL teams? Seattle, which is a top-15 market and the largest without an NBA team... and Vegas, which has the massive X factor of their entertainment industry.