S4: TIMESKIP! Everypony is older. Twilicorn takes over Celestia's spot in the show(cameo wise). The remaing mane 5 become background mentors to the new Mane 4-6, the CMC + new character(s). Whose the new pony of focus? Who else Sweetie Belle! Be prepared for the new title MLP: Song is Magic! 

Hasbro gets a whole new line of toys of mature CMC ponies, twilicorn and ......enter the sea ponies!