After several print runs of the Endtimes Book 1 Nagash, Games Workshop has apparently decided to release the book in softback. This will definitely help get the book out to more of the community, and I look forward to seeing it. Of course we expect this to be a less expensive release of the book, but time will tell.
Please remember at this moment of writing this, I have not been able to verify a softback release, so please consider it a rumor.
via Lord Shadowheart on Warseer
It seems GW stores were sent an email today, saying the End Times: Nagash Book would be getting Re-released as a softback, due it being so popular.