Well we'll have 3 opportunities next year since "Equestria Girls 5" is going to be 3 specials (most likely 22 minutes each) released whenever. I would hope they'll get brought back because they're both really popular and their fate was left hanging (plus the magic leaking into EQG-verse makes a good plot device for it).Then again, some characters of note have gone multiple seasons between appearances (ie Trixie, Gilda, Limestone and Marble Pie, and Chrysalis).