I sometimes wonder if the money in it would be in a store not even catering to gamers in particular. That is, instead selling access to comfortable meeting spaces of various sizes that would work for gaming but would also work for any other gathering of, say, 5 to 20 people. Set up something like that, you'll get book clubs, crafters, etc.
I've looked into the option of running a "mini-con" at times. Wouldn't be more than 30 people. The problem I run into is that there is home size that I can handle--about 13-15 tops. Then there are typical meeting spaces, which typically starts at around 50+ people size and is usually closer to the 75-150 range. Those are for company Christmas parties, wedding receptions, etc., and also come with a lot of other services that really drive the costs up.