That neither the DOJ or any of the states have joined in is telling. The way I see it, this is the Hollywood version of how the suit ends.
Court: You are alleging that the publishers, Apple , and Amazon are colluding to raise prices above the market level?
Plaintiffs: Yes
Court: And your evidence is that :
1.The publishers thought that Amazon was pricing ebooks below market value.
2.They and Apple changed the relationship between booksellers and publishers to an agency relationship, so that they could establish prices for their products at what they considered to be market level
3.That prices generally rose for bestsellers, while remaining steady or falling for other books.
4. That the only evidence of what the market price of best sellers are is the price of hardcover bestsellers, which are generally twice the new price of the corresponding ebooks.
5. That ebook sales, especially of bestsellers, have doubled in the past year, despite agency pricing, and are forecast to double again next year.
6.That there is no evidence that the publishers met secretly to fix prices on bestsellers or indeed any books.
Is that your evidence?"
"Yes, your honor"
Judge bangs gavel.
"Case dismissed!!"
(Of course, non-Hollywood, the judge would simply send out an order granting the defense motion to dismiss, but the Hollywood version is spicier

).
Its not enough to show that the publishers pushed for agency agreements or indeed that the publishers wanted higher prices. You have to prove a conspiracy to "restrain competition" . I don't see that here, yet.