Right off the bat the trailer opens with this portentous message, suggesting Black Ops 3 takes place in a world where the enhancements we're about to see are out of control.
The tease leads through sports doping and wearable tech and then this, showing 'wearable' integrated technology. It suggests the adoption of enhancements and body changing tech was a slow and insidious creep. Possibly taking hold without people really realising.
Building on the idea that mankind's technological fall is initially a gentle acceptance, we see modern day replacement limbs, cochlear ear implants, and this guy, Hugh Herr. He's a real researcher who lost his legs in a climbing accident and now heads up the MIT Media Labs Biomechatronics group. Those are his real robot legs. He's quoted from a TED talk he hosted, saying, "you will set the technological foundation for an enhanced human experience and we will end human disability'.
Having set up the idea of an enhanced human world we then get lead into the idea that discrimination against them is constitutionally wrong, leading to robo-sports people and a world where being 'normal' is to be disadvantaged.
This, according to the trailer, is the first 'networked brain to brain connection' allowing direct communication between minds, and presumably direct computer interfacing as well. The idea of feeding info straight into the brain is a staple of game HUDs, plus it also opens up the possibility of some head-messing 'what's really real?' type stuff and the idea of direct brain control against people's will.
The trailer then jumps to the idea of DNA upgrades and organ replacements, suggesting a progression from mechanical upgrades to biotechnological ones - much like the move from cyborg to nano enhancements in Deus Ex. It's setting up a world where humans are being upgraded and altered at a molecular level.
Enhancements reach the stage of being a luxury 'want' gadget, like this 'Courtoptic 2055 Retinal Implant', pushed in an advert as the latest must have fashion item.
Aaand now the downturn. Images of wildlife, fires and some sort of clean up suggest things have turned bad somewhere around the 2060s. There's mention of a fire at a bionics firm called Coalescence Corporation triggering riots and generally people seem unhappy. Confusingly there is an actual Coalesce Corp that "seeks, authenticates and implements advanced, game-changing technologies to accelerate the development of new therapeutics, diagnostics, and other highly beneficial products".
This Edward Snowden wannabe steps up to explain that secret military hardware is 'lightyears ahead of the retinal chips you can buy in the mall' and add that the technology 'we' use to heal is being used to turn human beings into weapons. So that's why hiding behind a wall helps...
It wouldn't be much of a Black Op if the U.S. government came right out and said "yeah, we're totally making modified super soldiers." But the intercut footage of... well, super soldiers in action makes it clear what's really going on. Also check out that futuristic/totalitarian-ish Great Seal of the United States.
As the not-super soldiers continue to attack, the whistle blower talks about voluntary limb replacement, just as the image switches to thermal to show this guy's robot arms and legs. Is this something the player has done to them? Or an optional upgrade path?