As several people have mentioned, I feel like the major win of using a local bookstore as opposed to Amazon is the social space it provides. I remember reading somewhere that in NYC bookstores were becoming places were smart single people could meet other smart single people.
Perhaps you could view books as a reason to be there, but not what you sell. A relaxed, wifi-heavy, comfy chair social space where you make your margins off selling coffee and sandwiches. Maybe even let people read the books without buying them. Keep a conversation going. Have visiting authors come and hang out. Like a cross between a library and a Starbucks.