Ok so I don't think a single next gen Halo game will break 10million sales. The reason I say this is because the series is on the decline (as shown by Halo 4 having poor legs, and online numbers being massively down), coupled with Xbox being decimated world wide and beaten in it's home country, which will mean that USA sales will stay the same/lower than Halo 2/4 (around 6-7 million) and with all gains the xbox 360 made in Europe and ROW being lost (and perhaps even more so) their sales will not break 2 million, confirming that Halo isn't a 10million per game franchise and that we still only have 3 (Pokemon, Mario and GT) Edit : I mean exclusive franchises by this point.

im done here.

I think it will break 2 million, but it won't top 4 million. There are a LOT of Xbox fans out there who just LOVE Halo...

Possibly. If X1 sold 50 million for example it would need a 20% attach rate which is incredibly high, higher than GTAV which was around 19% I believe. All depends on how X1 sells rather than the games themselves, unless they really do start to decline, which is possible but unlikely

halo 4 did not decline in sales since it´s trends over halo reach when you align the launches and you combine that with the fact that it already is before reach in all time sold on games on demand,
halo 5 will be at a minimum of 8 Mil lifetime, the only thing that could stop that would be an awfull beta

GTA?  CoD?  Elder Scrolls?  Battlefield?  FIFA?

Yeah, sure... Halo 5 won't sell less than 6 million!

not even GT anymore.

Guess we will see shortly if the game is going to move hardware or not.  My feeling is that the really DIE HARD Halo fans already have an XB1....

Who knows. Tons of people still have not upgraded yet especially 360 owners.

Halo MCC alone will do close to 2 million by the end of 2014.