I'm not sure "through a reputable publisher" cuts it as a recommendation system (though it could be a temporary workaroudn for now). I mean that guarantees one person read and liked it and at least some people edited it. I can more see review aggregation and charts being the solution to the "how can I find the good stuff in a sea of dross".

I think the market will change slightly although at the end of the day a book is cheap entertainment by hourly value (say a cheap paperback costs £5, it still takes you maybe 10 hours to read -- compared to £5 for 2 hours in the cinema).

I suspect the economics will work out similarly to bands -- as barriers to market lower, a job that lots of people are willing to do for free is a job which will have a lot of people struggling to make ends meet, making a loss or not making minimum wage. Previously books which would sell incredibly little were less likely to get publisher support. Hence, I would predict a rise of articles along the lines of "I can't make a living as an author because of piracy/cheap other books/lots of crap books preventing people noticing mine" type whinges as people who were previously self-published and unpublished are now published (but still not making any money at it).