Seriously Shasarak, it is not Mecheon's fault that your and our preferred IP is a bit player in a bigger company which is itself a niche subsidiary of a global entertainment corporation.
As to this decision, it is possible that they are ceasing the novel line because the movie was greenlit. The amount of revenue (that gets back to WotC/Hasbro) is negligible compared to the potential consequences of some bizarre event causing the new movie from moving from successful to unsuccessful (or the reverse). They just can't let author play around with their property for (I have no idea, let's say) a $100,000 revenue when there is a potentially $100 million movie on the line.
I mean, look at what Marvel is doing with their comics: Wolverine is dead and appears to be staying that way. There are no new mutant characters. All because Marvel doesn't own the movie rights to the mutant line and would rather grow name recognition for the Avengers and Guardians, etc. That, because movies are the main player and (like the RPG novels), the comics are a bit player.