“Contrary to our previous announcement, Deus Ex: Mankind Divided, which is shipping on August 23rd, will unfortunately not support DirectX 12 at launch. We have some extra work and optimizations to do for DX12, and we need more time to ensure we deliver a compelling experience,” the studio announced on Steam. “Our teams are working hard to complete the final push required here though, and we expect to release DX12 support on the week of September 5th!”
A few of the commenters on Steam have expressed displeasure at Eidos' failure to deliver on the promised feature (which was apparently a factor in their decision to preorder), but assuming all goes according to plan, this means a two-week wait, on the outside, for those sweet DX12 visuals—and it's perfectly playable (and will still look really good, I have no doubt) in the meantime. As the saying goes, it's a whole lot better than getting hit in the face with a brick.
If you haven't seen them yet, the Deus Ex: Mankind Divided system requirements were unveiled last week. Check your augs here.