According to the accurate Discord leak. xbox will have 3rd party consoles.It may be meaningless to discuss next xbox because 3rd party may make whatever they want. Maybe a $1000 high spec console or $500 lower spec console.
Challenge will be, how long will new games run on your $500 lower spec console? If its 3rd party, MS might just say, screw you Mr 3P HW dude, we want to release Gears of War super duper V2 MK5 and min spec is $1000 console.... How long will that take, 1,2,5,10 years?
I would rather buy a MS XBox or even just bite the bullet and get a PC.