I like the idea of Twilight as an earth pony.
I mean I have a rather extreme way of doing it, but hey.
Keeping Rarity as a unicorn and making Fluttershy a unicorn is nice. They are both the most elegant and it keeps to that classical unicorn aesthetic. I would love for Fluttershy to be a like a Pokemon Ranger almost, using her magic to ask animals for help with problems.
Sure she already does that, but made more explicit here. A deeper connection with animals through magic.
I have no positive opinion on Applejack at the moment until they settle it out.