Although I didn’t care for the shift from Chris to Declan in Executable, I’ve since come around to enjoying the books written from his point of view. But I think the change in recent books to focus more and more on Declan and Omega are a direct result of the whole Vorsook storyline. Basically, Declan’s abilities are much more effective against the Vorsook than Chris’. That makes Declan their Big Gun and puts Chris in more of a support role.
Of course, if the demons come back into play, that would change the dynamic. One thing that sticks in my mind is how both the demon prince and the Summer Queen referred to the Vorsook as the Ancient Enemy. Does that mean there could be some sort of human-elf-demon alliance somewhere in our future? That would be something to see.