The Amazon listing has since been edited to include a tentative release date of December 31, 2019, but for a while stated that Fallout 76 would be available on July 31, 2018 (you'll be able to view a screenshot at the bottom of this article). Again, not the end of the world, but you hit this story with huge replete branches 16,000 lines of dialogue deep and you expect some little moments with characters off to the side of the big arcs, and there just aren't that many of note. Unfortunately, this could be as much an error as it is the game's actual release date. From the teaser trailer, one thing is for sure that Fallout 76 is going to take place in Vault 76.
There have been brief mentions of Vault 76 in a couple of previous Fallout games, including on a Vault-Tec terminal in Fallout 3, in that game's Mothership Zeta expansion, and in a news broadcast played at the start of Fallout 4. Video games usually launch on Tuesdays or Fridays, and there's no good reason for Bethesda to buck that trend.
This means that if this is true, Bethesda is trying out a completely new direction for the Fallout franchise.
So we will code that ourselves the hard way, and provide a lot more support in optimizing the engine side of things.
Bethesda will announce more about game details at the E3 conference on Jun. 10, 2018. A Fallout 76 release date seems quite imminent.
More evidence that Fallout 76 is set in October, and therefore may very well release in October, can be found in the trailer. Since October already has some large titles releasing, there's a better chance that Vault 76 drops near the end of the year.
Similar to the release date, Bethesda did not announce the platforms of the game as well.
Ever since Bethesda shipped Fallout 4 back in 2015, fans have been clamouring to know about the next step of the franchise.
Another speculative suggestion is that if, as reported by Kotaku's Jason Schreier, Fallout 76 is a Rust-like experience, it may well be coming in early access form first.
Fallout 76 is in development for unspecified systems.