I can't leave it at that. Here's the problem with Usenet, from an syndication/blog reader perspective:

• Individual posts are "firehose". They just keep coming and coming.
• Topics (i.e. collections of related posts) are almost as bad.
• Topics wander off topic (usually degenerating to personal insults and Godwin's law type verifiers).
• Spam, spam, spam.
• Only a very small percentage of posts/topics will even marginally interest you, uinless you're a real sucker for punishment.
• Spam, spam, spam.

Generally, we can sum this up by saying this is the "needle in the haystack" problem. How much time are you, the reader, willing to spending tossing straw to find that one needle of information that might be of interest. I think this problem is crackable, but I don't think just feeds of posts or topics will solve the problem. Threading information in the post will, if the readers can take advantage of it.