Ultimately, far more effective spectrum use. Google Fi is an important step towards the ?quadrupling of capacity possible with radios that are smart enough to test the environment and then find spectrum. It works by testing the capacity/signal available in Wi-Fi, the Sprint network and the T-Mobile network. Using Wi-Fi well will allow offloading of 70-90% of all traffic. Being able to switch between Sprint and T-Mobile adds ?20% to effective capacity.
To make that estimate, I tried to find quality analysis of how much is gained by sharing spectrum. The pickings were slim until I realized I should be looking at the massive research on "cognitive radio." I found an enormously helpful compilation from the IEEE http://www.comsoc.org/best-readings/topic/cognitive-radio http://bit.ly/1GiJaTo
Know thyself applies to radio spectrum and networks just as it does to people. A radio that can observe and adjust will deliver data more efficiently and reliably. If it can communicate with those in the same space, they can cooperate even more effectively. (John Cioffi's "Dynamic spectrum management" and "vectoring" is showing the way.)