I personally don't like the firehose, but maybe it's a good idea.
Years ago we tried to make topics actually work. It never really gained traction because there just isn't that much attention in those dedicated areas.
Years ago we also tried tagging articles, but mods tended to be upset when we tagged many terrible articles as 'slow news day.'
Perhaps, the two could be combined to form not terribly specific communities that have a lower threshold for publishing and could be surfaced to the main page if it gets enough discussion. It's not quite a reddit implementation where communities are established with their own moderation bland, but more of a sorted version of firehost.
Right now, I don't use any of those and there are a large number of not really 'news for nerds' articles I don't care to read. Perhaps if I could just surf the 'newsfornerds.slashdot.org' or 'linux.slashdot.org' with more frequent articles then it would help both flesh out more articles and bring back a little niche.
It's something to think about... I don't really see a need to self moderated communities like reddit because of of the shit hole that can become, but realistically you need a way to lower the barrier to news aggregation. These side channels could be filled faster and maybe carry a disclaimer about the frequency of publishing.