It's confirmed for Summer 2020.
Kojima at Valve

Death Stranding is confirmed to hit PC in early Summer 2020. This was announced earlier today by Kojima Productions on Twitter. If you don't feel like waiting, there is still the PlayStation 4 release of the game coming up on November 8, 2019.

On the PS4 side, Sony is acting as the game's publisher. For the PC release, 505 Games will serve as the publisher. As it's 505 Games, it's a bit of a toss up right now on which PC storefronts Death Stranding will appear on initially. 505 Games published Control, which is still a timed exclusive release on Epic Games Store. However, they also published Bloodstained: Ritual of the Night after Control, and that was released on multiple storefronts alongside Steam.

So far, 505 Games has not issued any public statement about which PC storefronts they plan to release Death Stranding on. For some people, this could mean the difference between waiting at least six months for a Summer 2020 release, or waiting a year and a half for a Summer 2021 release on more than just Epic Games Store.

If nothing else, it's quite nice of Kojima Productions to officially announce this before the game was released on the PlayStation 4. That's above and beyond what a lot of other studios have done in the past for these staggered multi-platform releases.

In case you were wondering, the top image comes from a trip to visit Valve that Hideo Kojima took back in October 2018.