It would be nice to allow the launcher slot to be used to hold a secondary weapon, not just a launcher. I.e. a special operations force having a SMG and a longer range rifle at the same time.
This would work like ACE2's weapons on back system, except that switching could be done from the "mouse-wheel menu" (don't know what it's called). The weapons would have a set mass, and carrying heavy weapons would fatigue the player. This system would be useful for missions where two different weapons are required, or for special operations/diving missions, whereby one could use the underwater rifle when diving then switch to a "normal" rifle on land, with the option to discard the underwater weapon (still able to be retrieved later).