Are they still doing 'Unseen Academicals', or did the licence on that run out too?
Looking forward to the new series and I like the idea that'll be a continuation of the books rather than an adaptation. For me, a major part of the appeal of the City Watch books has always been the ever growing ensemble. Because of this I've always been a bit wary of them adapting any particular story since it took a few books for everything to really click. With that in mind, I think starting with the full cast of characters is the most appealing way to go.
In a way I think this is best for the characters too since they've become such a large an nuanced group that it's been hard to give them all due time in the novels.