I doubt it.

Nice prediction, valid but... I don't see things going that way.
They can have on par sales, but don't see Halo 5 obliterating Uncharted 4.

You think halo will sell to more than 50% of xbox1 owners?

It'll move a few consoles so that percentage would be lower.

Do some of you expect the X1 to sell 0 units from now until Halo 5's release? And 0 after it releases?

I seriously doubt it. Both Halo and XBox are brands on the decline, while PS4, Uncharted and Naughty Dogs are the present and future of gaming. Simply put in numbers, by this fall Halo will barely have a 15 million install base to sell to, while Uncharted will be a mega blockbuster selling to about 40-45 million gamers worldwide.
Halo 5 will be the lowest selling Halo ever, especially if it releases with a broken multiplayer again.

Interesting prediction, but I'm not sure it will hold, Halo 5 would need a crazy attach rate right away for this to happen. Naughty Dog are bigger than ever, even their remake of TLoU has sold nearly 3 million and the original nearly 6 million on PS3.
UC 3 has sold around 6.6 million roughly the same as the second one, Halo 4 has sould roughly the same as Reach, so both series are on uncertain grounds as far as the 8th gen goes but it deserves mention that Halo 4 is significantly down on Halo 3's lifetime figures and the series has changed studios/developer, which is usually not a great advantage, it is also considerably more prone to fatigue as there so many more games, not to mention that the former developer makes games that compete with Halo now, along with other franchises.

In my mind; the UC series has potential to grow still while the 12 million of Halo 3 was more than likely the peak of the series.
ND are a huge name in the industry now, more so than ever after TLoU, the PS4 will obviously have a massive installed base advantage, especially since UC4 isn't releasing in 2015. I don't think Halo 5 will come close to selling the 9.4 million of Halo 4, even if there was no series fatigue at all and the game turns out to be utterly mindblowing; the installed base disadvantage alone would make it very tricky to sell that amount in such a short time.

I don't think this prediction is possible, to be honest, it depends on many factors but the One was very few of the advantages in this particular scenario.

Regardless of the number I quoted, it's going to have to have a seriously high attach rate. 40%+

The point is, no game sells like that. Even the GTA, Halo, and CoD games. Generally, attach is install base times ~.2

If xb1 hit 20 million this year, that would only be 5m and that's IF it hit 20m.

Nope. Nap. Nep.

I'd take this bet honestly, because for one, I don't expect the game to actually release on time.