Something that never happened before, I would like to see the armors actually being affected by the environment, such as getting realistic mud, dust and scratches as you walk in a different scenario or being damaged by fire, wet by water and having water drops running down the armor.Well in a way it could be done. I remember the armour cracking in Reach but I suspect visual armour changes would probably mostly work in customising characters...though wet armour could work based on weather but that would take a bit of work....though not sure about mud since it be a lot harder to create the material/texture for. Either way it probably depends on how resource heavy it is and well Scarlet might be powerful but I think Infinite may be held back on the features to make it work on previous gen X1's unless they have room for scaling materials based on resolution per platform then there's resource management for weapon/vehicle/body spawning/despawning.
If Bungie did it well enough in Halo 3 and Reach then Infinite can make it a something we would have never even thought of on our X-mas list.
H3 had cinematic details that were cool like in Cortana opening cutscene. Now that I think about it. It would be cool if you could get blood on your armor. Struck by lightning. I mean let's face it chief is a walking lightning rod. Speaking of environmental hazards what if HUD or AI or something gave a heads up about sudden environmental changes ( cough flood spores spreading into the a area cough)