I think the direction to take would be to focus on the things that online stores can't provide. Clothes fitting, product repair, demo products to look at and play with, etc. Apple stores seem to do this quite well: they don't have hundreds of products on the shelves (online stores will always have you beat there), everything is nicely spaced out and you are free to walk around and play with the products. If you need advice or want to buy, you can talk to a sales rep. If you need something repaired, they do that too.
I was going to say something snarky about the 80s being the last time people did that, but there are occasional times I've had to go to a mall in the past few years, and I notice teenagers hanging out (usually in the summer).