What if all Hoppers and Super Joey connected direct to the router?
Theoretically that might free up enough, but Dish could never officially sanction something like that. They are only going to support what moca and standard cabling will accomodate.
My guess is moca could handle two hoppers + SJ most of the time, but there would be edge cases that will break it.
Moca's spec is for 175mbps under ideal circumstances. My guess Dish engineers are (responsibly) designing for half or less of that max.
For some perspective consider the following, admittedly unlikely scenario (assuming a sat stream is 10mpbs and OTA is 20mbps):
20 mbps - 2 SJ Tuner Streams
80 mbps - 4 Joey's playing OTA streams
40 mbps - Hopper 1 playing TWO (remember we have PIP) OTA recordings from Hopper 2
40 mbps - Hopper 2 playing TWO OTA recordings from Hopper 1
10 mbps - Dish on Demand download on Hopper 1
10 mbps - Dish on Demand download on Hopper 2
200 mbps Total
And naturally, if they allow an SJ with two Hoppers, folks will then want an SJ for each Hopper.