You could compare it to LAN intranet access versus the global web. The intranet access is just for a few people and basically due to limited amount of people is not focusing on economics at all since it’s not created for commercial applications.
So even though these virtual intranets with their own Safecoins could exist, these coins wouldn’t be worth much since people don’t compete for namespaces, are not attracted to build their website on something with few users and due to the low amount of peers data would most likely go slow and distant peers could cause higher latency.
My guess is that there will be one dominant globally accepted network, where businesses want to build their services on and are easily accessible from other safe-sites through links etc. This deeply connected network is where the value is at, creating a new network must have a really good reason for people to also join this one, and the next, and the next and the next… You will be paying for hosting on every separate network, why not keep it simple and already be at the one that is leading in data versatility and connectedness?
Sure mining could earn you more safecoins on a different safenetwork but they are only really worth related how much the network is used and it’s hierarchical/constructiveness value.