That's not jumping the shark at all. Also, a fandom is what people make of it, and you're always going to have jerks, catty people, people who make it too much of their identify, etc. but pony fandom will never die. After all, even if there is not FiM related content coming out, Netflix/DVD/YouTube etc. exists. Sure there'll be a lull for a few years when the show is over but then people will rediscover it.