There are two things going on here. The first is that "Launch HN" is intended for startup launches, as opposed to "Show HN", which can be any sort of project you want to share. If we keep the "Launch HN" title format, I don't see why it shouldn't be open to anyone who's launching a startup. That would be in the spirit of HN. But it raises moderation questions, like what do we do if someone posts a "Launch HN" and it isn't actually a startup launch? We're still figuring this out, so please be patient with us and hold off for now. We might drop "Launch HN" and stick with "Show HN".
The second thing has to do with YC's reserved slot on the front page, traditionally used just for job ads (see https://news.ycombinator.com/newsfaq.html), which we're extending to include startup launches for reasons I described here: https://news.ycombinator.com/item?id=13484644. That part will only apply to YC startups, similarly to how the job ads work.
Edit: if anyone wants to give us input about this, please email hn@ycombinator.com. Now is a good time because we're still figuring this out.