[pdx]

Yes, I believe that there is a non-zero probability that could happen, just as there is a non-zero probability that all the air molecules in the room you are in, which are bouncing around randomly, may all end up in the other corner of the room and suffocate you.

Since all nodes change sections randomly, like air molecules, they should remain randomly distributed, provided the network size is large enough. For a small network though, one can imagine you could get lucky eventually. Like other decentralized networks, security and size are related.