That's a real problem. How is "browsing the bookstore" going to work?
The "people who bought this also bought that" displays that some on-line stores use are an attempt at a solution, but not a really good one.
The "here's thirty feet of mystery novels," the new releases beside the classics, that you find over at a physical bookstore (or even an entire story-full of mystery novels, the specialty bookstore) is a climax technology grown over the past 150 years.
At one time, back when you bought the book block, then took it over to a bindery to put a cover on it (when the phrase "you can't tell a book by its cover" came from), the printers would hang the broadsheets in their windows, so people could look and read the first few pages. (That's also where the elaborate engraved frontispieces came from--attracting the eyes of strollers.)
Something will develop, I know this. What it will be? That I can't tell you.
Back in the early days of movies, before directors' names were put on movies, you'd find rampant piracy. (The movie industry developed in California because California was a long way from New Jersey, and they were abusing Thomas Edison's patents.) Folks would take movies, strip out the title cards, add their own title cards, and distribute it as their own.
One studio, to combat this, put the "Biograph B" in every shot of the film, somewhere in the background. Folks started to notice that movies with those B's in them were lots of fun to watch, and started to look for them. What biograph had, was a secret weapon: They had D. W. Griffith and Billy Bitzer.
E-publishers will develop. Some already have.
The mainstream publishers will dominate the market. They have the money, they have the backlist, they have the authors, they have the marketing experience.
But how will readers find new authors? That's the puzzle. I expect that the Book of the Month Club will re-emerge. If I were going to play this game, I'd set up a subscription-based distributorship, that every month/week/day/whatever sent a New Book to folks.
Maybe I'd call my thing "Jim Likes It," and people who shared my taste would get books that I liked. That would be a mix of mystery, science fiction, horror, true crime, and history.
Maybe it would work. Who knows?