Could it not be for Monarch or TUI or even a private operator. I can't see EZY using them when the fleet is moving toward a single A320 186Y operation. It was only a few years back that they ditched the 149Y 737700s so it wouldn't make sense to bring in CSeries subfleet. Again I think iit was EZY it would be to keep airbus on their toes and offering them more discounts or better terms.
Thomson is 189Y 737800 on the shirt haul and the EJets are already in the group so I can't see it being them. Monarch - well who knows. Stranger things have happened!
I'd like to see the CSeries get some success here in Europe.