Greg...
MWBCs have been around for a long time.
The deal is, because of the electronics and their embedded algorithms for detecting circuit faults, residential circuits are going all the way over to dedicated neutrals.
As this progresses, I expect to find the NEMA players to have crafted use specific circuit breakers for yet other circuits.
A lot of this is actually coming by way of the US Navy. They've had a DARPA program -- now getting on in years -- to entirely recraft the circuit protection logic of naval circuits. The Navy wants to move entirely away from 'dumb' circuit protection. Smart protection is to be built in -- up and down the line.
Eventually, the hope is that an internal smart grid will give combatant ships almost 'Star Trekian' diagnostic routines. This is but another way that Star Trek has lept from the silver screen into 3-D space.
