This bit of info pushes a hardcover copy of this book back until October. Now I am going to say that while I dont think that will happen, it would truly be awful if it did. However, on the good side of things, I dont think Games Workshop would pass up on its release and push it back behind Space Marines. Its just not logical, when Space Marines have so much (including 2 codex supplements) on the way.
The digitial copy of this codex supplement is up for pre-orders on the 13th (in a couple days), and I still expect the hardcover version of it to be released a few week later at the least. So no panic please, this is just a vague rumor at this point and we will keep an eye out for more.
Please remember that this is a rumor (lots and lots of salt on this one guys)
va DarkWarrior1981 on Warseer
I got the info today, that a physical copy of the Farsight book will be released, but not until october 2013! The digital version will go on sale July 20th as ibook and ebook (pre order from the 13th).