I don't think that you will see cityflyer operating into mainline bases anytime soon however if demand exists I don't see why cityflyer couldn't do other domestic routes ?
Kind of BACON ish during any downtime that isn't used for charter work ?
EDI-JER/DUB/MAN anyone ? Could provide some useful feed for AA at MAN or DUB but could well dilute BA feed !
Who knows ! Certainly the cityflyer brand/fleet could be used more.