Michael A. Martin has been reported to have indicated on Facebook that there are currently no plans for future ENT novels.
Well, there currently
aren't very solid plans for anything, since the process of developing projects for 2013 has only just started. So that's not exactly conclusive.
True, but I'm told that Martin indicated on his Facebook page that he thinks further ENT novels are unlikely unless sales on To Brave the Storm
But, as you noted, that's not a definitive end to ENT novels -- after all, that could change in just a few years' time if someone comes up with an idea that excites the Pocket authors and makes them think the audience will be excited.