Let's take the fact that there is already built in control for matrix switchers and all of a sudden we have a full blown switching system.

Four inputs means we could do:

Input 1: Up Stream Key
Input 2&3: Preview/Program
Input 4: Down Stream Key

Oh and it would be so easy to develop a little switcher control interface and with the right web interface....

Oh Wow how the ideas start to blossom.