Yeah what is desperately needed now for scaling is a way for subs to "tag" themselves with topics, that way you can widely filter off specific tags.

"Location" for example for town/city/province/state based communities, for example, would be handy. I can subscribe to the couple relevant to me by searching for it manually, but Id like to widespread block all the rest cuz I really dont need to know about the local news of a town on the other side of the world.

Same for Sports, really. I dont need the news for each individual sports team for each individual sport.