The media coverage for Halo 5 next year will push sales of the Xbox One. The console's install base will not be an issue.
And peak player count doesn't mean much. Halo 3 included everyone online, not just those in the multiplayer portion of the game like Halo 4 does. Halo fans liked the changes made with Reach, that is why 343i continued on with them and even advanced them.
Halo has changed; it's time we all change with it and just learn to adapt.
-Edit-
I guess it's not clear, I was responding to randomrosso. Not just posting random gibberish like some of you seem to think.
I didn't know people were waiting on B.net for three years for their registration to go through.
The performance of the predecessor by and large drives the sales of the sequel. With the entirely relevant nosedive that Halo 4's peak population has taken I doubt that Halo has the reputation to push the sales of the One in any meaningful way, especially given the One's price tag that's just overflowing with additional-value-it-doesn't-actually-have or however we're spinning that this week.
We're sitting at an average of 6.6% player retention going by the peak player population numbers (which aren't the best numbers, but 343i has for whatever arbitrary reason made the rest of the statistics unavailable as far as I know, where Bungie made unique player count public. This seems to be indicative of their entire strategy with Halo 4).
Customers want features - features that function out of the box on day one. Customers want theaters, and fileshares, and spectator a mode, and sensible map design, and decent gametypes, and generally a breadth of new features, returning features and improved features. In almost all possible realms of comparison outside of the actual gameplay itself Halo 4 was objectively worse than its predecessors. File shares outright didn't function for months after launch (where with smaller teams and fewer resources Bungie was able to have them functioning during the Halo 3 and Reach Betas and before the games were launched), theater no longer allowed for group viewing, Campaign and SpOps weren't compatible with theater, the UIs related to all of these features were clumsy and difficult to navigate, Forge had fewer features than in Reach, Halo 4 had fewer gametypes and fewer maps, there was no skill-based rating and the companion website is slow, messy and requires a scavenger hunt to properly navigate for stats.
Halo 4 did not supply these things, and I think it's unreasonable to expect customers to think that Halo 5 will.