Why is it a native app? A social/news network has no advantages as a native app and significant downsides. You're going to have 1,000x more difficulty getting people to try it if they have to install something.
Some more feedback: it looks like you're promising Twitter with a technology/entrepreneurship focus. That's like telling someone you're building an apartment building that only software developers will move into. You have to actively moderate the discussion (HN is one of the most heavily moderated social networks, if not the most). So what you're really pitching isn't a software issue, it's two things that have nothing to do with software: A) acquiring users, and B) making sure that they only post within your topic.
Like most social networks, it's not a software challenge at all. The software part is easy. The challenge is marketing and moderation.
To take it one step further: you shouldn't even bother to write your own code for this, since there are now a ton of open-source Facebook/Twitter/Reddit clones available.