In the book Ghosts of Onyx, you find out that there is a new spartan project, or at least there was. Spartan III's were created for the sole purpose of suicide missions. They were stronger than the Spartan II's, but lacked the military training, and were just sent on missions to die. I haven't read the book, but I believe they all died eventaully. They did have a new type of armor that was cheaper, since they were going to die anyways.
As for the Spartan's armor in the trailer, no one can really tell what kind it is. There are so many variations of the MJOLNIR armor, that it's very hard to tell from a glance.
Outside tripping in the broken city.
Outside kicking in the broken city,
there's nothing wrong with that.