That's certainly true.

Battlefront on all platforms will sell less than Halo 5.

Do you mean all platforms combined even?  If so, why do you think that is possible?

Yes, all platforms combined. Battlefront on PS4 + X1 will sell 8m and Halo 5 will sell 8.5m. 

I seriously doubt that Halo 5 can hold COD back on Xbox One.   I really believe that Star Wars has similar mass appeal.  I predict at least 5 million on Xbox One and 6 million on PS4 minimum. 

I expect less than 5 million Halo 5.  The reason why I think this is because of the install base compared to Halo 4 release.  You're 8.5 million unit prediction will require over 50% attach rate.  I am predicting a modestly healthy 30%

Wouldn't comparing it to the install base of the 360 when Halo 3 launched be more appropriate?

I choose Halo 4 because it is the most recent mainline release. I would like to clarify that I mean 2015 sales. Lifetime is much harder to predict. You raise a good point though. 

Understandable. I just think Halo might have Zelda-syndrome at this point, where the first game on the console is bound to sell the most due to exposure and legs. I mean, according to VGC, Halo sales on the 360 go down with each successive entry (3 > Reach > 4), so that may very well hold true on the XBO as well. I guess we'll see.

As for 2015 sales, 5 million definitely doesn't seem like an offensive prediction. I thought you were referring to LT, lol.

Halo 5 because it is such a big brand, also the best selling star wars only sold 5m on the Wii

A lot of faith is going into Star Wars, even EA believes its 10 million goal is achievable, however that's a lot of units sold for a game with only Multiplayer only. That limits its audience by quite a margin. Titanfall went on to sell 2.6 million on X1 and 4.4 million units across 3 platforms while Plants vs Zombies GW only sold 2.2 million across 5 platforms. I know its Star Wars but I cant see it hitting 10 million units lifetime with just a Multiplayer mode. Halo I can predict 6 million in its first year and possibly 10 at the end of its life. Halo does cover more of an Audience as it offers both Single and Multiplayer modes so its a game more for everyone which gives it a bigger advantage.

Battlefront 2 sold 6.6 million on 4 platforms in its total lifetime sales while Battlefront sold 5.4 million across 3 platforms. Based off BF history, i see it selling around the same total units 6-7 million. I think Halo 5 will sell 6 million units in its first year. I also think Halo 5 has alot more legs then Star Wars because again just a multiplayer game which will probably burn out alot sooner then a game offering a full solo campaign aswell as multiplayer.

Just my opinion.