I'm not too sure about how things will go, but take this as a pinch of salt coming from someone who only knows about this series on a superficial level.
FiM was the MLP reboot series that started a phenomenon... like, seriously, a
huge cultural phenomenon. I'm not sure if lightning can be captured twice, but I suspect that expectations will be high given the success of G4 outside of its target demographic. Some people will thus inevitably set themselves up for disappointment as they have honed their own personal expectations for how the new series will be like, so whether or not Hasbro listens to the fans there will be dissenters no matter what.
Also, there's the fact that this is a continuity reboot to begin with. This may or may not go well given that humans are resistant to change, and to see the characters they've known for a decade reimagined for a new generation might be okay for some, but may also turn off other staunch G4 fans who will not give it a chance.
On the other hand, I also suspect there will always be the actual demographic who won't care for the quality and possible flame wars I already foresee, but it's really too early to tell. Hasbro probably knows a lot is at stake and likely want to capture that peripheral demographic again, but as I said, I'm taking a very outside view of this whole ordeal.
