Just because Rarity likes to sleep around doesn't mean she can't be mature. It's not like she was ever portrayed as immature or a ditz, just really horny.
I was missing the Sweetie Belle and Officer comics, and then this comes up and mows us over with a brick of feels. He seems like a such a great upstanding citizen. But who knows... Sometimes bad things happen to good people, and we can't do anything about it. I do think they'll go down that path, look at the tags placed on Tumblr. Loss of innocence. If he was just injured I doubt they would put that as kids don't really get that affected since they think they'll get better. But like, death. Death is something touchy. Even adults have trouble with it. Or who knows, maybe he'll be maimed and live with a leg wheel chair thing, like this dude:
Link. I mean, seeing someone you really look up to have to be restrained to a wheelchair or something similar is really sad and can mess some kids up.