As the most negative voice in this discussion, I will give some credit to what I've been seeing in the few samples dropped by Hasbro.
First, the new show runners appear to have a good idea of how they want each character to be portrayed. Even though I've been harsh on the character designs being too similar, the behavior differences are clear.
The Earth pony has some similar traits to Twilight Sparkle. The thirst for knowledge and addiction to learning.
The Unicorn is comedic and extroverted. Few fucks given. Brave enough to trespass in a place her kind isn't known for welcoming others.
The male Earth pony. Comedy relief of a unique male perspective. Similar to Rainbow Dash in some respects.
If the writers can maximize the tropes of each character and the things that unite them, a good story can be created and presented despite the limited physical characteristics.
The subtle movements in the new animation does give hope that this won't bomb as badly as the first Disney (not Pixar) 3D animation movies. All processes have a learning curve and each studio had to grind through the curve by making films.
I still strongly dislike the character designs so far.