lets say the series x is as powerful as a 2080 super, it will be stuck with that until whenever microsoft decides its time for a revision like the one x was to the base model one, at the time of the base one release, nvidia's latest gpu series was the gtx 7xx series, during the lifespan of the xbox one we had the gtx 9xx, gtx 10xx, and gtx 16xx/rtx 20xx, thats 3 generations of nvidia graphics cards, if history repats itself, there will be 3 generations of nvidia graphics cards during series x's lifespan, which anyone with a pc will be able to upgrade to, this isnt even taking into account future developments by intel, amd, things like mainstream ddr5 ram, etc