I suspect the more profitable end of being in the brick and mortar coin store would be the purchasing of items coming in off the street more so than items going out the door.
That being said, my small town has two LCS on the same block. One guy has been there at least 35 - 40 years and it seems to be a hobby more than a profession. Nice store, professional all around, but inventory does not turn at all. You really need to negotiate him down and it is simpler to just walk next door.
Second dealer has been on the block for 10 years now (switched buildings recently so we actually had three LCS on the block briefly). Inventory turns over rapidly. A lot of items seem to be priced just where you can't flip it on
ebay for a profit, but you need to do the math to be sure. Items are graded right, priced right, and the place is often busy. I have been 8 deep in line recently. Closes up shop most weekends (which seem to be the busiest days in his shop) to travel to shows and make deals. Does not do the
ebay thing, but deals with other dealers that do only that. Lots of great retail items and lots of great numismatics you just don't see in town. He had an 1856
Flying Eagle cent for about a week, and same thing with a
Gobrecht dollar. Just sitting in the case with a bunch of other coins I was trying not to drool on.
As a business man, I admire the second guys business chops greatly. Still think it would be more profitable from a sales perspective to go online only. I assume the retail store front is value added only in purchasing coins, not selling them.