That concept art is by Liquid Development - they helped to make some of the armor for Halo 4. Hayabusa was concept but it never made it to the final game@Megalodon 302
I was just talking about this studio. I didn't know that Halo 4's multiplayer armors were not designed by 343i. Maybe that could explain some things ..
They designed some of the Armor. Not all. 343 was going more of, "What if 3rd party company made Mjolnir armor just like how it's mentioned in game"
And the Reach MK VI doesn't look to simular to the Halo 3 one either. For it is supposed to still be a prototype model. So comparing a Prototype MK VI helmet with a Gen 2 model that was produced 6 years later. That's kinda crazy