The downside is that everything's ephemeral. I've long thought there was room for a private network where you can pub/sub to people you care about. Sort of a simple and private Livejournal / Blogger.
FWIW I think the self-hosting bit isn't where the opportunity is. It's in hosted private sharing. One thing I'd do is create landing pages for people who want to share privately and have $$. Parents are the first group that comes to mind.
I wish you success - the world needs what you're doing!