Fallout 76: 10 Take-Aways From Bethesda's E3 Conference
10. The Fallout Universe At 76
The trailer showed dwellers from a control vault beginning to explore the wasteland as a form of prequel to the existing games in the series.
Many institutions we know and love aren't present or active yet - there will be no New Californian Republic, Institute, or Brotherhood of Steel - although a trailer heavily implies that the origin of this latter group will be part of the story.
Since no games have been this early in the Fallout lore, Bethesda have an opportunity to branch out a lot in terms of monsters, level design and worldbuilding, and it's likely the game will focus more on newer creations than older fan-favourite weapons, items and characters.
It would be odd, however, if there were no references to the way the world is in later games. There must be a reason all the crazy monsters we see aren't in Fallout 3, which is relatively close by geographically.