Penguin and Random House Merger

So Penguin and Random House are planning to merge, which I think is utterly insane. Why? Because my feeling is that they publish the bulk of the books in this country. There are two of what are called the "big six" (or is it five?) publishers. But in fact, they are the two biggest--or that would seem the case to me. I decided to take a look at my own bookshelf and see what percentage of the books are from these two companies. Here's how a random shelf of nonfiction books (since I work for a university press, I decided to include that as part of the percent too):

Here's how it looks for fiction:

Nearly half! Seriously, the best fiction generally is being published by these two companies; HMH and Harper both publish their share, but it's nowhere near to the amount that RH and Penguin do. I hope, but I doubt, that antitrust will keep this merger from going through.

The argument these companies will make--and it's not necessarily unjustified--is that they now, in the digital age, have to compete with media giants like Amazon and Apple, who will increasingly create their own content and/or dictate price schedules. Being bigger gives these two publishers more leverage, but what of the little guys? Will the heft of a bigger publisher translate to better/fairer deals for small presses too, or will it simply mean that one has to be big to play?