You're not making much sense friend, "Lowest option should be less than 5 million". 2 million is less than 5 million...

I make fine sense friend.

anyway, fw should be 3.6-3.8 million WW

Let's try again

You:

"Lowest option should be  less than 5 million". 

Me:

2 million is less than 5 million...

I think I know what the problem is... I didn't properly mark my first post. However, if you are still confused after this than I don't know what else I can tell you. So let me redo my orginal post.

Here it goes: Lowest option should be "less than 5 million"

For first week sales, I expect a mild increase over Reach and 3 due to releasing closer to the holiday; and pre-order numbers seem to suggest a mild increase as well. For ten weeks sales, it's obvious that it's going to be higher than past Halos because it's going to be during a much more active period. So for 1st week predictions and first ten week predictions, I can understand the higher numbers, but I don't see why a lot of you are expecting such higher first year and lifetime sales.

Looking at the first 52 weeks of Halo Reach and Halo 3, there was absolutely no increase from 3 to Reach. They were both around 8.2m give or take a few thousand. I see nothing that suggests that Halo 4 will magically blow past those numbers into the 9million range. Yeah, it has slightly higher pre-orders, but that can be attributed to it's November release, rather than being an indication of higher long-term legs. Sales appear to have stagnated for the Halo series, if not declined. However, I'll ignore the current trend and will predict Halo 4 will have a better first 52 weeks than both 3 and Reach. At best, I see about 8.6m for the first 52 weeks for Halo 4. And that's being considerably leniant for Halo 4 imo.

Serious question: Why do you people expect such massive increases for the first yearl?

As for lifetime sales, I'm pretty much certain that it's going to do worse than Reach. Halo Reach's legs were way worse than Halo 3's legs. Halo Reach was selling about identical to Halo 3 for about 60 weeks. However, at the 60 week mark, I don't know what happened, but Reach's sales came to a crawl in comparison to Halo 3. With that said, there's nothing to suggest that Halo 4 will have stronger legs than past games. Not to mention the fact that the Nextbox is supposed to release next year. That gives Halo 4 only one year to sell to the primary Xbox console. After that first year point, I expect Halo 4's legs to drop in comparison to Reach. I'm not saying it's going to have shit legs. But in comparison to Reach, which had three years to sell on the primary Xbox, I'm expecting Halo 4's legs to be a bit lower. 

Halo Reach had three years to sell before the Nextbox released. It sold on par with Halo 3 for about 60 weeks, but dropped off after that. Halo 4 is going to have one third the time that Halo Reach had before the Nextbox releases. I see nothing to suggest that Halo will somehow reverse the trend of dimishing legs and that's without considering the impact that the Nextbox will have. I'm expecting somewhere around 9.5m (give or take 500k). It's gonig to have a strong first year, but it's 2nd, 3rd, etc. years are going to be much weaker imo. 9.5m is still excellent though considering it released when the next gen has basically already started.

tl:dr - It's going to have a great first year, but relatively weak sales afterwards.