If they ever want to expand on the world of MLP, I think they have tons of good opportunities to do so with a spin-off series. Sorta like the Friends Forever comics, a different set of characters to focus on. It'd be a good way to introduce the rest of the world instead of staying in Ponyville. What do you guys think?
I think an Equestria Girls series is possible, depending on the success of Friendship Games. It would almost certainly have different writers and animators, though.
Hard to say. I'd guess not, since they've fleshed out most of the main character potentials for this hypothetical spin-off about equally in the current series. We could potentially see a sequel series where the current characters are all much older and we have children/other new characters to deal with.