Peak in Software or Peak in hardware Sales?
Hardware: Likely. If current tendencies persist, Xbox gonna sell something in the 6M line, maybe even 5M line, this year. Nothing suggests a recover, numbers are going to keep going down and Xbox Series X/S may end under 50M life time.
Software: no clue... but Xbox had a very weak gen. so far, imho. It's kinda easy to to deliver a "Peak Year" atm, the bar is low.