This is how I’ve seen P2P commerce evolve. In the offline world, newspaper classified were sub-divided by location, and each paper covered all categories. Then Craigslist blew that up using Internet scale. Now there is so much liquidity in online P2P commerce that each vertical can support its own destination, but they cover all locations. I’ve said something similar before.
I was going to write a more thorough blog post on this subject, but I think these images tell the story more cleanly.