Except that's clearly not how it's gone. We've a long (over four years) thread discussing the possibilities of an upgradeable console - it's clearly been a concept worth considering. And MS has been all about the software ecosystem, which was why they even got into consoles in the first place. An upgrabeable console would be a first, and a unique selling point for the platform to compete on. While the competition is offering you the chance to rebuy your old games to play on the latest system, MS can offer the software convenience of PC and mobile, with all your catalogue moving with you to your next device. And even cross device, which would be spectacular. There are plenty of pros and cons, all discussed in the relevant thread.