There are currently limits on the number of connections at any one time, but they are separated by type. we can have a different limit for global (remote internet connections) and local network connections. Sometimes a particular protocol is more expensive than others - for example, I've heard reports that webrtc has big problems when you get more than 4 connections (which is a big problem if you are trying to implement a DHT, but not a big problem for ssb)

A big part of what gaurantees the eventual consistency of a gossip network is the randomness - because if there is some chance that you'll connect to a given peer, you know that you will eventually connect.