I’ve put some info about this in my topic about the DLC:
Complete checklist of all DLC
But I’ll copy it here for you as well:
This is all that has been said regarding pre-order DLC being released to the public so far, (to the best of my knowledge):
> Was the armor that was available in the PAX build the full set? If so, why is there no Mark V armor?
> The PAX build contains the full set of armor in Halo 4. In the final game, there are a variety of methods for unlocking armor and armor skins - ranking up, earning commendations, progressing through Specializations and completing goals on Waypoint. <mark>Some of the skins, helmets, and the FOTUS armor are exclusive to various retail offers. Some of these items MAY become available to all players at a later date.</mark> We wanted to focus on the Spartan-IV armors for Infinity, maximizing the amount of variety across the armor designs. However, we did want to include a reward for completing the Campaign on Legendary, so we decided to use the Mark VI armor as that reward. While we’d love to include every historical variant of the Chief’s armor, it’s just not possible to fit more armor sets into the available memory.
Source: The Halo Bulletin: 9.5.12
So, basically, the answer is we don’t know if it will be released in the future, just that it MAY be.
Another interesting point is the apparent contradiction that was made regarding the Locus and Deadeye helmets…
> Last week, retailers began announcing their Halo 4 pre-order bonuses. The first eight bonuses you’ll see below are skins. (For clarification purposes, please note <mark>they are skins only, and we are not locking away armor.</mark>)
Source: The Halo Bulletin: 5.30.12
I’m pretty sure there’s no other way to unlock the Locus or Deadeye helmets in-game.
The Locus helmet was made available via the King of the Hill app and the Deadeye helmet featured in the V Energy Drink giveaway, but both of these promotions have now ended, so technically these two pieces of armor are now ‘locked away’ from players.