Re: Halo 4
Orion's Best-Case-Scenario Speculation!
This is basically me interpreting what the changes could be (or how they could be implemented) to maximally benefit the gameplay experience.
Joining in-sesson games
Provided that you can't join into a game that's 80% done, this is great and I don't know how you could really object to this too greatly
Instant respawn
In non-objective based games, this seems fine to me to implement, such as in free-for-all or team deathmatch games. For objective games or ones relying on the ebb and flow of combat (such as Invasion and Grifball) instant-spawing would unbalance things, and so there should be a minimum time before you can respawn.
Dedicated co-op episodic content
So long as it doesn't replace campaign co-op functionality, or is just plain old Firefight (or even like ME3's multiplayer which is objective-based Firefight outside of defending generators) I wholly support this. The content that is won after each round of missions per week, however, should cover more than just the mission of the Spartan-IVs are on, otherwise it could get boring quick.
Sprint is now a default feature
So long as there isn't infinite run (or armour abilities drain from the same energy source) this pretty much avoids becoming an unbalanced feature and one that should have been around long ago given the capabilities of the Spartans.
X-ray vision armour ability
If you've got this equipped, then motion-sensor functionality should be disabled. There's no need to have both when each of them informs you of the enemy position. Extra functionality like spotting items through walls would also be nice.
No Elites in multiplayer
This is only a good choice if the armour customisation available to the Spartans has gameplay-related effects that are balanced, so that different Spartan setups can be very different gameplay wise. Such as heavy armour providing better defence once the shields are down, but slowing you down, or extra optics in your helmet enabling an extra level of zoom for all weapons, but at the cost of being more susceptible to headshots.
Potential loss of Firefight mode
If a big part of Spartan Ops pretty much becomes object-oriented Firefight, then this isn't really that big a loss, since it would be incorporated into a bigger, better system.
Abilities unlock as you rank up
Instead of gaining abilities, you gain ability and equipment tweaking, but it affects only your loadouts. The modifications you apply to the weapons or armour abilities in your loadout won't translate to equipment picked up in the middle of battle. Again, balanced tweaks like I proposed with armour - expanded magazine at the cost of damage-per-shot, faster rate of fire with less accuracy.
Multiplayer being VR missions aboard the Infinity
This could be interesting if it's used to include a further expanded variety of multiplayer maps and scenarios than in a more realistic setting, even fairly zany ones. Otherwise, making it VR instead of 'IRL' combat is meaningless when it doesn't translate to gameplay.
Loadouts
Ideally, loadouts would only be made use of in maps where set equipment or loadouts are not already set, and not include high-powered weapons such as the rocket launcher, sniper rifle or shotgun. Instead, those could be replaced with weaker equivalents like the concussion rifle, DMR/BR and mauler.
Weapon drops in/cycle through random locations
This would be downright bad if the weapons just dropped anywhere willy-nilly. Instead, I think they should cycle through a variety of locations, where once the weapon at one place has been picked up, the next place starts having subtle visual indications of where it will next pop up, but that can only be noticed when you're already close to it. Such as a glowing floor plate on a Forerunner level, out of which will ascend the weapon on a pedestal, or in the instance of an orbital-drop weapon cache, a series of glowing laser markings on the ground.