It will happen the same that happens with the Hondas: once it has become a "cult" item, the lower the edition the more collectable....
I have two copies of that book. I bought one new, and other one on ebay. When it was getting already expensive, I took a chance and bid low. And what usually happens, you end up winning the bid on the article you really doesn't need.... :-)
It is a good thing that the book will be in print again. Ot it is just it will be re-printed provided the are enough pre-orders. I also have the "Original Kawasaki Z1" and I have to say that series of books are fantastic, in both the informative and photography sections.