You could say the requirements for running a full node will be going down, as well. A great deal of nodes are going to operate in pruned mode. Sure. some nodes will receive the full chain from several sources, but what about the great deal of nodes that will only hold 1-2GB? The overall ratio of transfer will be much less than 1:1. Your also ignoring a very important factor: Nodes are already up. If you add a new node to the network, and it had to get 84GB, it has 5000 nodes to do it from, not like it some crazy stress to the network. If your unable to download '84GB' or whatever the real number would be, than you can operate a full pruned node with just a few GB, or SPV client.