It would like exactly how it is today. It's not hard to find someone not charging anything for the same piece of content, or not charging anything for another type of content that fills the same void.
I really don't think what's stopping micropayments is the technical ability (or even business deals) to do so. Stuff like that have been talked about and tried for more than a decade, it never caught on.
Anyway, I don't know? I would go somewhere else. Maybe I would just walk outside? It's not like what I get from HN is essential to anything I do in life.
Where would you go?