Welcome to Waypoint, Hotdeadfox! Great to have another long time fan here on Waypoint. I'm a lore fan as well (read all the books). Not sure where Halo 6 will go after the hot mess that was Halo 5 (from story perspective), but I just hope Atriox is involved as a main villain regardless.
Yeah it's a tough one especially for people that didn't play halo wars 2 they would have to do another introduction to his character. here are my thoughts on 6 that i put in another post.
I just wish they would answer some of the big questions like the answer to the flood that was mentioned by cortana in halo 3 which was ignored later in the story so they could go and destroy truth. Also the librarian who is in another galaxy who is being looked for by the other didact also mendicant bias who is buried on the ark who was speaking to chief in the terminals in halo 3. So many loose threads that if they pulled them together would be immense. SO CHECK THIS.
Mendicant becomes chiefs new ai (which could tie in to the arbiter and lock cut scene in the mcc which looked like they were on the arc and the scene with chief in his poncho that also looked like he was on the ark.
also the changes the librarian made to chief in halo 5 enables him to control and have better understanding of forerunner tech
The flood return which means we could have a need to go to the ark to find the final solution to the flood, which then enables chief and the infinity to find the spirit of fire and bias like I've said above.