Intelligent Message Routing
PubSub Control plane can be more smarter if it can detect which subscriber is closest in proximity and forward the message to that. It can borrow the traits of GLB. If the subscriber is busy replay the message but this time it should go to next nearest subscriber. There are certain trade offs but I think it will be a worth feature. It will reduce the egress cost of data transfer and keeps the data by default closer to the customer. It will also work well with the regional resources behind GLB which wants to generate messages.