I understand that some people don't jibe with Facebook and want me to move away from FB comments (I've received several requests). If I do that then I'll have to write an auth system. Not difficult to do but I'd rather focus my time on content right now. Eventually I plan on implementing an auth system and including Twitter and Facebook logins. Once I have that I'll probably move to an in-house commenting system. I can always export the comment data using Facebook's API later to keep the existing comments.
As far as the audience goes, I know you're not alone in this but the people who have boycotted Facebook aren't the majority of users (even HN users). They're just a rather vocal group. ;)
For now I think I've got most users covered for their commenting needs.