I don't think what you are searching for exists. Everything is now online and can be obtained for less time and money by ordering online. I am starting to get EVERYTHING that way because it saves so much time. There still ARE small bookstores--new ones have opened in Manhattan recently, but I notice that they combine books and gifts in order to survive, and often seem to have more of the latter. Browsing a bookstore is a different experience from ordering books online, and there are still people who want to buy books in a bookstore--especially parents who want to take their kids to look at and purchase books. But those rents!
What I long for is a good Pilates studio with well-trained instructors and equipment-based classes. I am certain there would be demand for this--but just as certain that it's not a big-money business, and it probably would not work on 37th Avenue. I go to a great studio in Forest Hills that is located on a side street. It seems to be doing well. They offer a variety of classes besides classic Pilates, including massage and bodywork workshops, belly dancing, etc. They rent space to a massage therapist, too, another way to make a business like this more viable. The classes at this Forest Hills studio are MUCH less expensive than those at similar studios in Manhattan, which also helps make it a big draw for people who work in Manhattan and could also attend Pilates classes there. The most popular classes are always fully booked with a waitlist. Could something like this work on a side street here? Maybe combining Pilates with yoga?
Someone mentioned co-working. I now work at a co-working space in Manhattan, WeWork. They are taking over the city, opening new locations everywhere. It's a great concept--it becomes a community as well as a workspace. You get connected with everyone else who works there via an app, and they hold classes and workshops and free meals often open to everyone who is part of the WeWork community. And there are other similar co-working spaces popping up everywhere. Maybe that could work in JH--but not in one of the small storefronts, maybe in Bruson.
I agree with the idea that what people really want here IS food/drink related, offering things we don't currently have on 37th. As for what else might work in one of those storefronts? Beats me. There are lots of empty storefronts all over NYC, not just here, of course, and empty malls all over America. Combine that with these stratospheric rents and the fact that landlords can get tax benefits (I think) from keeping their storefronts empty...and the future for small stores just does not look good.