120 fps and 8k makes it sound highly unbelievable.
It'll just mean it supports 8k output, no games are going to run at it. PS5 I believe was already confirmed to support 8k. At best maybe BC Original Xbox/360 games will run at 8k.
The original PS4 supports 4k for example, but it can only be used for Media.
Predictions (Made July 2019)
LTD: PS4 - 130m, Switch - 110m, XBO - 52m 2019 : PS4 - 15m, Switch - 18.8m, XBO - 4.8m 2020: Switch - 22m (Peak Year)