I'm thinking that this is a few things, many of them rather mercenary.
Amazon does an end run around publishers, printers and writers' agents. Writers with agents push for bigger profits (which they do anyway) and withhold their product if it isn't as exclusive, thereby driving up prices for quality. Agentless writers may end up being like union scabs. Traditional publishing companies shut their doors to unsolicited manuscripts (to be fair, they have been doing this for years as it's a flood, mostly of crap).
I also predict a slanted payment structure in favor of Amazon and the franchises, and the writers will have no bargaining/negotiating positions whatsoever.
Sorry - I am a total cynic. I equate this to the kind of work and profit that can come from writing for The Examiner - read - a lot of effort for nearly nothing, and the vast, vast majority are suckered into it because of the success of very, very few.
Further, what happens to fan ficcers in franchises that don't support this? Will their legal departments crack down even more, despite the fact that this fan fic (e. g. our own) is out there and not for profit? I like not being sued.