There's no reason a single email can't turn into a solid long term friendship if things click. Some of my closest friends live across the country from me after meeting online.

Friendships don't materialize out of thin air, you have to start somewhere. If you would like to become friends with people on HN, posting contact info in your profile sounds like a good place to start.

I met half a dozen very good IRL friends first through online discussion (though not on HN).

The thing about talking to people online is that you can use the medium to agree to meet up in person as well.