Here's a really off-the-wall idea, and it probably has plenty of legal implications too. But just as a "thinking out loud" exercise...
Many of the customers that use liquid yeasts are (or become) quite adept at handling them, propgating them etc.
I wonder if a smaller LHBS could pick, say, half a dozen or a dozen of the most popular liquid yeasts and set up a yeast bank. Make a starter out of each and refridgerate and/or freeze the crop into smaller vials. That could alleviate the storage problem somewhat. Then, they could sell the vials directly to people who have the smarts to make their own starter, or for a few bucks more and with 48 hours or more notice, create a new starter ready for pitching.
Of course it would require an investment in money and time, and there are obviously many potential pitfalls,
Then again, maybe I just need a few more beers and a good lie down.