Maybe it'll like halo 2. Some part of the game we'll be played by masterchief and some parts would be played by Arbiter. Masterchief's story would be his dealings with the death of cortana, him being given a new AI but with a twist, maybe cortana left a few data or a tiny tiny bit of her inside masterchief's armor and then that would be like a gateway for cortana to control that AI like what she dis to the covenant's AI then poof there's cortana again but of course there would be some malfunctioning still because the previous AI which cortana corrupted would be fighting her and regain control for sometime until cortana fights back, that is if and only if they dont replace the chief's armor with new armor tech. But i doubt that cuz chief already has the latest mjolnir mark VI. OR Chief would find a piece or shard from the ruins of remains of composer or the ship contacts infinity and tries if there's still some parts of cortana in that shard or piece. Afterall, she did say most of me is down there. But there's still a lot of theories to what john has to accomplish to get through his problem. Now for the arbiter's story, maybe he's fighting the storm covenants and at the sametime trying to return back to earth to assist john or if ever earth gets attacked by some random storm covenant fleet, he'll come back and provide some help, hopefully then the two guys would meet then poof just like in halo 3, john and Thel' would be fighting side by side again. And at the end the didact will return from the dark abyss of the slip space portal thingy which he fell into. I think he was just stunned by that bomb. Not killed. Those bombs could kill a ****** promethian knight with one blast much more will it take to kill the didact. Btw i think thats the original didact not the bornstellar one. Or vise versa. Then maybe a prediction in halo 6 ending. If cortana doesnt go human or even,like the promethians, get a body like them, maybe they'll find another composer and digitize the chief, if he's that desperate to be with cortana, aaand there they'll see each other talk talk talk then some alone time. )))) well those are my opinions of course but all i know is that the next halos would be so much more better than halo 4 because of all the feedbacks 343 have been getting ever since.
