Because this right now is only a small part of a novel and mainly dialogue at that I'm not going to go into an "advanced" rating as I really don't think it would be too beneficial. Instead I'm just going to focus on the dialogue because it seems to me that's what you're really wondering, the whole "does this work" question. Correct me if I'm wrong.
I should say I'm somewhat interested in the idea of seeking out a self-published man for whatever reason. I'm interested in John's motivation for that, so that's a good thing. But dialogue wise, it's my opinion that you're sinking into a bad territory of being too direct about your own personal views of the publishing industry in your dialogue. I can't say that's true because I don't know what you actually think about the publishing industry, but I can tell you that it was the first thing that popped into my mind as I read this piece. That can be a good thing, but it's also insanely problematic. Your characters should try and be as detached from the author as they can be in their dialogue. Dialogue like this seems really forced. Your characters shouldn't naturally be pointing out all these faults or ideas, or if they do, they shouldn't be articulating it in this "I agree with everything you said" way.
That's really the main problem with this. The dialogue isn't reading as natural to me because it seems so focused on criticism. Criticism isn't bad, if a person's novel can't make a point about something, what's the point of even publishing it right? But there's a difference between making a point and telling a point, which is what I fear this dialogue leads towards. I can't suggest any one way to fix it, that would be too problematic. They are your characters and I lack too much background to give them a convincing dialogue. I would suggest going over the dialogue with a critical eye. Analyze the importance of what these characters are saying for the progression of plot. Are they saying these things because they need to be said or are they saying them because you want them to be said. There's a big difference, and while it's fine for you to want your characters to say these things, I really feel you have to make your audience want these characters to say them too.
I know that's a bit cryptic, but hopefully you can squeeze some goodness out of it.