Hard to say until more facts come out about what may or may not have been going on behind closed doors. I do not have a great deal of confidence in the current Justice Department, and some times the government entities move too quickly into a new arena, like eBooks, before there is a chance to see how things are going to play out. In those cases, the action can make it worse. But I suppose it is possible that the mere existence of an anti-trust investigation could loosen things up if there is in fact a lot of collusion on prices.
Complex. I read the US investigation as a reaction to the EU one. The EU has very different anti-trust laws from the US; here, it's legal for manufacturers to set prices and command retailers to obey those prices, at least some of the time. In the EU, my understanding is that their regulations are substantially different.
There are probably some publishers sweating a little bit right now, though.
For me? Cursing the day. I am hoping, hoping, hoping that the governments involved will PLEASE let the publishers continue with agency pricing. The longer publishers continue offering ebooks for $12-15, the better things will be for indie writers. Indie books already control a majority share of the top 200 in pretty much every fiction genre. Just let the publishers continue hoisting themselves by their own petards a little longer, please...
If agency pricing goes away as a result of this, Amazon will slash big publisher prices to the bone, and we could see books from large publishers actually begin competing with the more expensive indie books on price. Indie prices are beginning to climb away from the 0.99-2.99 range and into the $4-6 range as self publishers gain more confidence in themselves, which is a great thing - but the last thing we need is big publishers pushing out books for $10-12 that Amazon discounts down to $6-8.
(Yes, I am enjoying having a competitive advantage at the "Big Six's" expense. )