To answer both questions, let’s just take them in order:
1) I think Ashleigh Ball said it the best when she was at BronyCon January 2012: Bronies will always exist so long as My Little Pony exists. That is something I will stick by. I have no worries about the fanbase fizzling out even after the show is over because with all of these fan projects coming out, the show’s legacy will still live on and not to toot my own horn or anything, but I think Journey of the Spark will help revive the interest in the show even after its over.
2) Personally, I don’t really care which direction Hasbro takes the My Little Pony brand when FiM ends. Just so long as they are able to take more chances with getting top tier talent on the brand and creating new shows and stories and ideas that fall in the same line of quality as FiM, I think the property will last for a while. That’s what I think anyways.