According to the interview posted earlier, G5 was limited to 5 ponies due to the limited amount of minutes a movie could actually show, so they didn't have room for another. With the series some time in the future, that kinda changes doesn't it? We could very well end up with a 6th!
If you had control over it, what or who would you add? Do you want to go with another unicorn to balance out the cast? Or should we bring in an exotic Kirin of Hippogriff to really shake things up?
Discuss below!