Too many hardware revisions and upgrades is what killed Sega, combined with the disastrous launch of the Saturn. MS needs to focus on AAA exclusives, not new hardware. When most of the XBox One library can be played on PC, that's a big problem.
More power isn't enough of a reason for people to upgrade when the current generation is powerful enough for most gamers. Without strong exclusives, its just going to end up getting high-spec multiplatform ports that also appear on PS4 and PC. We're at the point of diminishing returns, so how many people will buy a new $400+ console when most of the games on the XBox 2 will be on PS4 and PC and look nearly as good?
Upvoted for being insightful! Hope to see you on more of my posts :)