As time progresses, new companies will come about and more will break down, there will be new people in the industry too but less jobs. There will also so less jobs which get paid a large sum and books will become cheeper.
Publishers get up to 80% of money made per book (minus other costs such as printing) In the end they are lucky if they get 10-15% after these costs are taken off. There is a huge risk that a book won't return all the money that was put into it. Harry potter 7 was of 8% book revenues that year (an example of a very successful book).
In 2008 US sold $24.2 billion books. There is now not much focus on book sales anymore but everyone is now interested in e books instead. For the average author: gets about $3000 if he sells 5000 books and even more shocking is that only 5% of books break even.
At the moment the publishing industry isn't doing too well indeed. The eBook sales have topped the hard copy sales and the gap is increasing. The Kindle, iPad 2 and the Nook are all out competing and selling better than their opponents, the publishers. Also 'Print on Demand' and 'Accessible Publishing' have been flourishing recently as they are a much better concept. Print on Demand is a setup that allows the publisher to know when someone buys their book so that they can print of a new one instead of printing thousands in one go hoping that they will sell. Accessible Printing is a way of helping those with reading disabilities by making the font bigger or changing the font colour, they do this by making various copies online.
Unfortunately for publishers, the numbers aren't working their way. EBooks are selling more and more digital copies of books than the publishers are. They are selling more because they appeal in more ways than the hard copies, for example you only one device to bring thousands of books wherever you want.
However, this rise in sales could have the opposite effect. Because the books are made digitally, they are open to piracy. The 'pirates' could drive the authors out if business because they are giving them away for free. This could revert the figures.
Unfortunately though I do not think that that will happen as we live in an age where huge breakthroughs like this are followed up with improvements and sooner or later the piracy of books will be stopped.