I could see another network (CBS or FOX is all that's left without any fairy tale shows) picking up a series that is very similar to OUAT
. Networks like to copy each other rather than be stunningly original. Cable might get into the act - TNT or SyFy for instance.
However, I haven't heard of any fairy tale shows in development other than the ones that have been picked up. Lots of witches and ghosts going begging, tho.