At what point is that a solution looking for a need rather than the other way around? Of course it is more complicated than that - people won't come unless they see it already, but they can't participate unless it exists already.
What if you consolidated football, fútbol, hockey, etc. into a "sports" community? And movies + TV + videos into a "media entertainment" one? And LEGO et al. into "toys"? Fortunately PieFed offers an incredible amount of support for fragmentation of communities with multiple tools.:-)