Could be like this
Xbox Level 1 - Current XBox spec, redesigned with modular/upgradable design.
Xbox Level 2 - $100 upgrade, bumps the system in hardware power by double (2.4 TFLOP) making it more powerful than a PS4. 1080P + 60 fps becomes kinda standard, great for VR.
Xbox Level 3 - $250 more but allows games to run in 2K/4K resolution with effects that would blow away a regular X1/PS4. For really hardcore gamers.
Upgrades are subsidized by MS so they're basically sold at cost, so they're not pricey like PC GPU upgrades which are sold at a large mark up.
Individual upgrading to the metal like being able to swap RAM and stuff isn't possible, you pick one of the above configs, this gives developers a better idea of a fixed three set of hardware to work on.







