Cerny was so on the money, it aint even funny....
4.2TF was not going to do 4k at ultra settings/high settings, so cerny knew he had to do something to get a crisp image on a 4k screen with a reduced footprint from 4k native, hence CB. He knew 6TF could not do it, hence why so many XBONEX games are at 1800p and below. Even some 4k games on the XBONEX are way below ultra settings like PUBG with medium to low settings and yet awful framerates......and even some of the games where XBONEX try to push too far in terms of rez are lagging behind the PRO in the framerate department, some even with worse graphcial settings like in Fortnite.......
Yes, 8TF seems likely to be able to do this gen's games at 4k at ultra settings at 30fps/60fps....I'm pretty sure if the XBONEX had 8TF it would be able to do even it's own first party games at at MAX settings at 4k. So like PC, Forza 7 would have all sliders to the right, Gears, Forza Horizon etc.......at ultra settings.