I would not take out anything. I would add more variety. Some more armor unique armor designs, for example combining Elite honor guard, Elite Zealot, or some Brute design, armor design with the MJOLNIR for a pretty interesting look. Since the guardians are all over the galaxy, bring back the brutes,drones, Prophets, some new aliens, the flood since it stands to reason that there has to be some installations out there that the flood are still captive. With everything that is now for one big war with unusual allies or not however it will go, whatever happens it would be a epic war. I would like to see some Elite Zealots and honor guards to act as body guards to the arbiter. I liked how in Halo Reach that every mission there was a special elite to kill, little plug ins like that would be nice. Some more night missions, maybe some dual wielding. Maybe a game mode that is pitch black with no motion sensor and you have to use a flashlight to see, to eliminate enemies. More a variety of weapons, I didn't mind that there was different versions of each weapon, but after the years of advances in technology along with obtaining some tech, the old weapons should look slightly different and new weapons you should see a good combo of techs. Not a assault rifle with the scope of a light rifle. A version of the assault rifle that fires the hard light that don't home in, clearly showing that there is human ingenuity with tech recovered from the Promethean. Something like that as a example. Lastly I would like to some stuff from the Halo novels be included, for example the precursor from Halo Cryptum. I think that's it.