On last week's supplement, it certainly does suggest that GW don't see another DoS-style book as being a worthwhile investment. That said, since DoS, GW have pulled White Dwarf from the newsstands to try and improve footfall to the stores. This week and next week's issues both have free stuff for 40K in them, all of which is designed to get even more people into the stores (it worked on me, I hadn't been in one for months before last week). So the switch from book to free giveaway booklet has a purpose for GW and isn't them just washing their hands of it.
As far as I'm aware, the license still has two or three years to run. Presumably GW couldn't just sit on it and do nothing with it. Licenses usually have clauses in them to prevent that from happening (which is why Sony keep churning out Spider-Man and X-Men movies). That's not to say it'll require them to keep producing new product, but it might require them to produce something new every so often
Bilbo wrote:
I do not see a new book being released unless the Silmarillion is released on film!
Sadly I don't think Christopher Tolkien is going to sell the movie rights to it.