Deus Ex: Mankind Divided [official site] can be completed without killing anyone - even the bosses. This as confirmed by the game's Executive Game Director, Jean-François Dugas, in a tweet responding to the question. If you're a fan or familiar with Deus Ex, or particularly Human Revolution, then you'll understand why this is significant news. If not I'll explain below.
Deus Ex Human Revolution is one of my favourite games and it was universally praised upon release. It was also universally criticised for its boss fights, which abandoned the feeling of freedom that defined the rest of the game in favour of forcing you into a closed space with a single enemy you had to kill in order to progress. This meant they were a slog against bullet sponges, but worse, it meant that it undermined the character you were attempting to roleplay.
The boss fights seemed a baffling decision from a studio that otherwise knew what made Deus Ex special, and the reason why became clear shortly after release: the boss fights had been outsourced to a different company. The studio ran out of time to do them internally and so had to scrap their initial plans in favour of something simpler.
There's reasons to be positive about the boss fights next time around. In our interview with Dugas at the time, he said that "I think the biggest weakness there wasn’t the concept of having boss fights, it’s just that our boss fights are not Deus Ex boss fights and that’s why people are complaining about them." I'm inclined to agree and Human Revolution already has its example of a grand, Deus Ex boss fight in its DLC, The Missing Link. Set aboard a cargo ship, its centerpiece is a boss who you can approach half a dozen ways, including defeating non-lethally and whose special weapon you can steal before you fight them.
Better still, that Missing Link boss fight wasn't designed as an afterthought in response to the criticism: it was the originally planned design for Human Revolution's very first boss fight, against heavy soldier Barrett. This was mentioned in the excellent developer commentary on the game's recent Director's Cut release [Steam page], which makes the fights more interesting (although still unavoidably lethal). The impression is that Square Enix Montreal knew how to make a good boss fight all along, and Dugas' tweet suggests that this time they're committing the resources to doing so.