Ideal scenarios can happen 100% of the time on closed platforms, developers create the ideal scenarios, it doesn't just happen.
Xbone's software development kit will handle the brunt of the work in terms of bandwidth allocation much like 360 did with eDram.
PS4's bandwidth pipleline is like one huge ass fire hose pouring water out of a tank at 176 Gallons an hour, while Xbone's bandwidth pipeline is a set of hoses, the main hose providing 68 gallons an hour, with 4 other hoses (move engines) feeding a combined 102 gallons an hour reserved for the higher bandwidth tasks. Not everything needs high bandwidth all the time and that's where the move engines come in. When done correctly the system does still combine a total of 170GB/s of bandwidth.