I was wondering about that when i got the notice that sandstorm will be coming soon.
Will it be any kind of skin system ? or Will it be any DLC's in the game ?
They "kinda" answered that question within a Q&A
visual customization and appearance is coming, for the soldier and weapons.
F.e "weapon skins" and things like, "heads, boots, torso" etc.
Regarding post-launch and DLC nothing specific was said yet.