Well i have for sinced i played ep. 3 always through that carley wouldn't comeback, but i was looking some vidoes for the scene were Lilly shoot her,
and like we all know this box apeare "carley Won't forget that".
Well maybe she'll return, it's not impossible... Otherwise the note would be really useless.
When you choose to save shawn over duck, it's not like shawn wouldn't forget that cause he died....