Most readers don't pay too much attention to a book's publisher. They see the product at hand, the book, and credit the author as its creator. The rest — the editing, the formatting, the cover art, etc. — is mostly absorbed subconsciously. I know I never paid attention to which publisher was behind what book before I dove into this whole book game.
That's all going to change. At least, that's my prediction. The fact is, the book market is super-saturated right now, and it's getting harder and harder to separate the good stuff from the... not-so-good stuff. I'm all for indie publishing, but the fact is, technology has made it so easy that many people are banging out stories and throwing them up on Kindle unedited. Readers are often surprised and put off by the number of grammatical errors and typos they find, and they're starting to pay more attention to where a book comes from.
Also, there's a reason why readers always go back to their favorite authors: they know what they want, and they know where they can get it. If you're looking for hard futuristic sci-fi thrillers, you pick up a Michael Crichton novel. If fluffy romance is more your thing, you look for Danielle Steele. And when you've exhausted all the books from one author? You look for similar ones. Again, with all the authors out there, it can be hard to tell who you should take a chance on next.
That's where publishers come in. Or sometimes, publishing imprints. They each represent a certain brand, and I think readers are going to become more aware of that. In a way, publishers are going to become like fashion retailers. If I'm a shopper looking for something cute and quirky, I walk into Kate Spade. I may not know exactly what I want—maybe a green cardigan? maybe a striped dress?—but I know their style suits my tastes. Similarly, a reader in the mood for a fanciful space adventure will visit Aliens & Spaceships Press (I just made that up), perhaps not knowing exactly which book they want to read, but fairly positive that they'll find something that suits them.
Publisher's won't just be confined by genre, just as Kate Spade isn't confined to selling handbags. It'll take time, but I think eventually a publisher's brand will become as important as a designer's label. What do you think?