You are somewhat wrong about how urbit works. Stars and galaxies don't really work as routers. They are more like DNS servers: they provide the peer discovery

You are somewhat wrong about how urbit works. Stars and galaxies don't really work as routers. They are more like DNS servers: they provide the peer discovery mechanism, translating from urbit IDs to public hosts and ports. Most communication is peer-to-peer. Software updates still flow down the tree from the root, but as I understand, they are looking to make that more flexible, though this poses some technical challenges. When you have an urbit planet, it's yours, and no star or galaxy can take it from you. There isn't a "lease" arrangement, it's bona-fide cryptographic ownership. Comets are currently served by the galaxies and can communicate with any other VMs that are willing to talk to comets, and at this stage in the network, that's basically all of them.