I'm interested to see how this will work out. I don't have Instagram and I don't really want to 'get it' either but I do want to see what this is like and whether it's social like Facebook or more open like Twitter. I'm also not sure if people will really use it all that much.
Either way, if I was Elon I'd be kind of worried, especially as this has the added bonus of being propped up by Instagram rather than being largely sperate from FB / IG.