I am not really worried about this whole Equestria Girls thing. At best, it will be a fun spinoff in the vein of Daria, and at worst, I won't watch it. It's not like it it will have any effect on the mane show.
I am far more worried about what will happen tomorrow at 10:30EST, because that has the potential to be a major shark jump moment. After three weeks and hearing arguments from both sides, I still am kinda negative to Twilicorn. Does that mean the show will suck? No. At this point, we don't even know if her change is permanent. However, when I watch S4 and the finale, it will be with zero expectations of greatness.
One thing is pretty much for sure. The Faust era is fading into the rearview mirror and fast.