I like the idea of the guilt about the fire causing Carla to fall off the rails into another addiction. Soap disasters almost never have long term consequences for characters, but it seems likely in this case Carla will lose everything because of the fire. Of course we know she has nothing to feel guilty about, so I hope Tracy's part is revealed before Carla leaves.
Soaps love piling on the disaster after disaster for favourite female characters. I'm not sure why...
It would be nice if Carla leaves Coronation Street on a happy note.