Said this before, and I am going to tell it again. If MS does not manage to get their shit together next-gen, the Xbox brand is good as dead and will follow Nokia and Windows (for mobile) into the grave. No amount of second-rate studio purchase will mend the damage that was done in the past 7-8 years.
I might agree if they hadn't expanded the "Xbox" brand outside of their consoles. Their focus has shifted somewhat away from consoles and if next-gen they have a worse performance I imagine the presence and focus they have on console gaming will be very limited after that.
As long as they keep making gaming products in some capacity the Xbox brand will live on. Even if they stop making consoles they might still produce accessories and controllers under the Xbox brand. PC has an Xbox app for their games and gamepass, Xcloud will be xbox branded, etc. But in terms of relevance the Xbox brand is at it's lowest point since 2006 or earlier.
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)