Many games (Tom Clancy's GRAW, GRAW2, GR:FS,...) have an animation showing when a player is aiming down the sights of the weapon, shich is visible both for AI and other players in multiplayer. It'd be great to implement same in the ArmA 3.
Reason:
1.You can more precisely see what are your teammates doing
2.You can tell whether the enemy is scanning surroundings or aiming for some target (and has tunnel vision ATM)
3.Added immersion

I reckon it can be done same way as reload animation works now.