The writers are probably setting him aside at the moment because they have plans for him that can't be fulfilled at the current place in the show. Plus, Iris most likely has less time left. Her place is in Unova, mainly in Opelucid, where she will eventually hone her skills and become champion. Cilan, though, doesn't continue with being a gym leader, as shown in BW2. He'll try to become a better Connoisseur. If you think about it, Burgundy and Cilan also speak a little bit of French, I believe. The new Gen VI region is supposedly based off of France. Maybe that is the origin place of the Connoisseurs, where the best go to complete their training and become an S-Rank. Cilan could go with Ash and probably have a huge role.
I've gotten into IV Breeding. I'll breed any Pokemon that can, just ask and I'll see what I can do!