The XB1 is nowhere near as popular as the 360 was when halo 3 came out, plus you had a lot of former PlayStation users jump ship back then which also helped increase sales.

But things have changed a lot since 2007. Bungie no longer makes halo, nor is the series the juggernaut it once was, due in part to 343 turning off a sizable percentage of old users with halo 4 and MCC.

The game still sells better than many other games however, but it's certainly a franchise that is past its prime and is in major decline as a whole.

1st line, talking absolute shit

2nd line,

This could be dragged out because these type of debates usually are so I'll just leave it to you to work this one out!

I do really think that Halo 5 has the highest % of game sales as digital out of anything currently released for several reasons:

1. It's created for online gameplay which offers many months or even years of content and gives a very high replay value.
2. The Xbox rewards gave 6,000 credits for purchasing this digitally which translates to $6 so since its a game with great replay value why not grab it at an effective $54 launch price if your planning to play more than just the campaign and then it trade in.
3. It would be many peoples "go-to" game for quite some time so having it digitally and able to launch it without changing disks all the time between their other games ( yes people are lazy and some see this is a valid reason alone to justify digital games)

I'd expect the digital sales of Halo 5 are around 35% (maybe higher) of the retail sales and that the current sales are somewhere around the 4.5M -5M mark.

I...what? Did you read my post? The attachment rate means nothing and even if it did, that rate isn't going to hold. MS is going to sell like 30-40 million more consoles this gen. Halo 5 sales aren't going to keep up with that.

You can't just compare install base percentages for two games and say one outperformed the other because it has a higher percentage.  Sales of any individual franchise do not go up linearly with install base so a percentage of userbase is just a fun factoid without enough information to compare two games with different install bases.  

As an illustration here's a graph of madden sales in the US compared to X360 install base.

This is by no means a linear relationship.  Now it's possible that Halo series does have a linear relationship but you can't decide that based off two points (since you decided only 343 developed games count in a later post).  That simply isn't how math works and an assumption of linearity in an install base to individual game sales relationship would only make sense if all other franchises which had enough games to come to a conclusion had had a linear relationship between the two.  Obviously given the example I just showed you above, that simply isn't the case.  

Obviously, developers and publishers are more interested in attach ratios than actual sales! Duh!

Well like it or not. When was the last time an exclusive title SIGNITIFCANTLY drives hardware sales? Its been a long time, and that isn't happening anytime soon.

http://www.amazon.com/gp/bestsellers/2015/videogames/ref=zg_bs_tab_t_bsar

The Best Selling console of 2015 (Amazon) is the Nathan Drake Collection at #15

What the Fuck Dude ?, this dont have nothing to do with the Install Base, when a Game like Halo, Begin to Sell less this does not means nothing with Install Base, this have to do with the Fan Base, that will buy the Console to play the Game (or who already have bought it), If Naughty Dog, launched a Crash Bandicoot 4, the game would Sell more than 7 Millions like their previous entries, same with Mario Kart 8, 11 Millions of Wii U, and 6 Millions of units sold, like Final Fantasy 7, that will Easy Surpass 10 Millions in Sales, the name of this Magic thing are "Fan-Base", if the Peoplel ike Video Game and the Franchise, of course will spend over 400US$ to play the next Main entrie of the Franchise, and Of Course there aways have the People that dont are Fan of the Franchise, but buy the Game because the game is Nice.

For Example, Mario Kart 8, on the Wii U, is Nearly out-selling the Mario Kart from the Game Cube (that had twice of the Install base) this means that from the Game Cube, until nowdays the Fan-base of the Mario Kart Series, still the Same  Despite of How much Consoles Sold.

and for Ori and the Blind Forest, Not even one place says that it Sold Better on Xbox, i dont Know where you have those Ideas, a Indie Game will aways sell better on Steam, than on Any Console, Even Rocket League, that if was not gave for free on Playstation Plus, there would be a lot more Players on Computer, than on Playstation 4.

I Will say what i said Again, the Game is over 2-4 Millions Budget (ori) Microsoft, receive 70% from the Pc Version, and 100% from the Xbox Version, because the game is Fully Digitall, so if they sold 100 Thousands on Pc, and 70 Thousands on  Xbos One, in the First Week already would be Profitable, so we Dont Know how much Ori sold on Xbox, and it did not sold more than on Steam, this is the True, even a free game like Rocket League, Struggled to have more players than Pc, and on a console with more than the Double of Xbox One's Install Base, and i dont Remember Xbox, Having a Plataform Mascot like Sonic, Mario, Crash, so Plataformer is not a very popular genre on Xbox.

Other Thing, they've Stated that Halo 5, was The Best Selling Digital Tittle ever on Xbox Store, on a "Oppening Week", this Also dont mean that Halo 5, surpassed Ori and the Blind Forest, in Digital Sales, this only means that he Surpassed Ori's Week of Launch Numbers.

For Microsoft, you need to use the "Oracle's Eye from the Heavens" to Read the PR.

so with the "Digital Attach Rate from Nowdays" The Last of Us, sold over 14 Millions, and Driveclube, over 3.4 Millions ?.

You Cannot Compare numbers that you Know 100%, with Numbers that we Dont Even Know,  if Halo 5, only did over 3 Millions in the First Year, and Halo 4, did over 7 Millions, this means that the People that Played Halo 4, did not liked it Enought to Buy a Xbox (or the Game Itself) and Play it, this means that those people are  not Really Die Hard Fans of the Franchise, You Cannot compare a Person that Bought a Xbox 360, to Play Skyrim, and Fallout, and use As numbers that "Halo Now sell more with a lower Installbase" of Course, if even with a 80 Millions Install Base, this does not Means that the Fanbase is the same, those 3 Millions of people that purchased in the First Year, are the People that are Fan of the Franchise, and already had a Xbox 360, did you Really think that Halo 5, will Surpass Halo 4, in Sales even when they Release New entries of the Franchise ?, this Only will happen if they Bundle  the Soul of Their dogs with the Game, and sell it Together with the Console.

You just proved my point exactly. It was bundled. That's what I just stated.