There is a lot to be gained if a LDS could actually get out there and just fricken dive! Certify your divers, then take them places local. The more you can get them diving and build up the community, the more they are going to want to stay involved, need to buy from you, more likely to return for more training, stop in the shop just to say hi and pick something up, etc. Build the community and they will come.
This community-based aspect to the economic viability of a dive shop seems to be a recurring theme in this thread. I am just not so sure about its general validity.
I will use myself as an example. I live in a northern climate. I am the only diver in my circle of acquaintances. I have no interest in cold-water diving. I have a cottage on a lake, and have dived it, but man o man, once I hit the thermocline, it's full stop. I have no interest in purchasing a dry-suit and related gear. I very much enjoy taking dive trips to the warm blue water, and the using the money cold gear would otherwise cost for that. The same goes for any additional training - no cold water, thank-you.
There are 3 local dive shops with whom I have done business:
Dive shop #1 is located in the suburbs and is very small. Their primary revenue is from PADI courses. The staff seems somewhat disinterested in general. I will probably never go there again. They have a dive group associated with them. They go on local cold water excursions throughout the summer, and there are about a dozen participants. They also organize annual trips south, but the prices are not reasonable at all. The members do seem to enjoy it all, but that's 12 people in a city of 2 million.
Dive shop #2 is located in an industrial area north of the city. Their main business is tank fills. They do it for fire departments, industrial facilities, other dive shops, etc. They have only a very basic showroom, with a high volume of used gear. It's on the way to my cottage, so have used it for tank fills. Other than that, they serve me no purpose.
Dive shop #3 is in the city, and is new, large, beautiful, well stocked, and staffed. It's a nice place to be. They too market PADI courses agressively, but there are often people there buying westuits, BCD's reg sets, etc. They have a very good selection, and often, specials. This is my go-to place. They also organize annual trips south, but the prices are, again, not reasonable. I am unsure and doubtful that they have an engaged and active associated community, but they are in my opinion a model facility.
I have for the moment and forseeable future, all the gear I need. Only photgraphic equipment is on my shopping list. So, none of these shops will make a considerable amount of money from me. They already have. It's done, and for me, there is no local community to join that will be of economic benefit to a dive shop. My community has developed through the people I meet on dive trips.The shops depend on a steady supply of fresh meat, but this is Montreal, not Florida, and divers here are presently sparse.
For dive shops 1 and 3, they need to sell PADI courses first and foremost. They know and admit this. They need a generated interest in diving.
I got into diving on a whim at a resort. There was a little booth poolside. I meandered by, and being in the holiday state of mind, took a moment to investigate. As soon as I got in the water with the gear on, I was hooked.
Whenever it comes up between myself and others that I am a diver, the responses are without exception ones of amazement and curiosity.
So, perhaps this is what the industry needs to address the problems that DRIS mentioned on the other end of this split thread that got the whole thing started; a massive and sustained marketing/PR campaign. A big bright global kiosk. To raise awareness in the general public. To get out of the niche. To get people interested, curious. To get them to go out of their way to an LDS on a Saturday afternoon. To give the dive shops more opportunity to do their job of training and selling. To think globally so that there can be action locally.
But I might be wrong.
). Life is change...we don't need to make diving great again. It's already great. More options than ever. We need to adapt and enjoy. I mean really, what's the alternative? You can't put toothpaste back in the tube. 
