My Little Pony: Friendship is Magic - Image #503,263

No one cared who she was til she put on the mask.

Just because Twilight isn’t being replaced doesn’t mean that new members can be added to the mane cast. I still think it’s Shining Armor and Cadance, but I could very well see this character playing some sort of role.

As far as the earth pony speculation, I cannot tell if she’s a unicorn or not. I can’t tell with that mask.