Both The Originals and iZombie have been left off of the schedule for the time being, although both were renewed.
From what I read no mention of Reign either it was renewed too.
and Originals is midseason, so 2017
I figure it depends on how other shows do, the new shows, and izombie and reign also show up in 2017 sometime.
They will just plug them in where they need them.