It is no different than reddit. Eventually one community will have the momentum to dominate a space and everyone will gravitate to it over time.
The only feature I think we need is an admin curated keywords option for mods to add in search results for communities. Like people often search for bike when they mean bicycle. The old reddit community name for bike repair is called bike wrench. It is the same here. The main community for bikes in general is Bicycle. People may or may not find communities based on these keyword differences.