Remember that brief period where all of your PC games were in the one place? Yeah, that's becoming a mere memory now.
It would seem that Bethesda is wrestling back control. Fallout 76, both beta and final release, will only be available from Bethesda.net. This means that no, you can't get it on Steam, or other services such as GoG, for that matter.
So far, a lot of people seem unimpressed by what 76 has to offer, and in a sense this makes it a perfect test-bed for Bethesda to trial controlling the marketplace with. If it sells respectably enough, this suddenly becomes a bigger story at the likes of Rage 2, as well as the next Doom, Wolfenstein and, eventually, Elder Scrolls games could very well follow suit.
This isn't great news from the perspective of a nice, neat virtual shelf - indeed, it feels a return to the CD/DVD Rom days when you had to create and curate your own games folder - but it has to be said that Valve has done a pretty amazing job of burning through a lot of good will recently. Or maybe people are just speaking out at last.
In any case, if you want to play the next Fallout game on PC, you've got one option and one option only.
Fallout 76 is slated to launch this November.