Ok so today I’ve read into many posts and this is my base theory for the story…
So after Halo 4 SO, Halsey is working with Jul. I believe Halsey will abduct a human and make it into a Master Chief like Spartan. This Spartan is trained to be against the UNSC. This spartan would be the one at the top as it’s reflecting MC. I think MC is in search for the little hope that remains for him and he doesn’t have a side. I believe 343 will truly expand the campaign in a good way and allow both characters to be playable. Leave your opinions on my theory or what you think! 
There’s just one error with that theory and that is that the spartan in the picture has an ONI insignia on his chest. Wouldn’t make sense since ONI tried to kill Halsey .
Ya I noticed but they might’ve stole it somehow
i like the idea tbh, if it wasnt for the oni symbol on the new spartan D:
but even so i dont think halsey would try to replicate the spartan II’s now, to me she seems to think of them as her children cutscenes
in the first scene she immediately defends them, especially john
even in reach she reacts differently to jorge than to the rest of noble 6 
It’s extremely difficult to create a Spartan, especially a Spartan II. Even under closely monitored laboratory conditions, most of Master Chief’s class was either crippled or killed by the augmentation procedures. So I don’t think Halsey, as brilliant as she is, would be capable of producing a Spartan on her own, especially with Covenant technology. Halsey also did not train the Spartans, that was Mendez, so her Spartan would have no military training what so ever. The Unknown Spartan also has an ONI insignia on his torso, so I believe it’s simply an ONI operative. Your theory is, well, creative, but it’s based off of practically nothing.
Yeah, except the glaring problem is that Jul 'Mdama has the technology or supplies in order to create a Spartan.