I think it'll take some time before My Little Pony and its fandom will get to the public eye in the same way Star Trek, Star Wars, superhero comics or something like Dr. Who have gotten. For example in its beginning the Star Trek fandom was quite small and the original series was cancelled due to low ratings, but nowadays it's almost like common knowledge.
Ultimately it all depends on how Hasbro hadles the franchise. Will there be a completely new generation again, or will they aim for more continuity like they do with Transformers and keep building on the current universe? The latter would help to keep the current fanbase.