Being stuck with your decisions does make some sense for an online connected world, since a big part of the game will be choices and consequences as they relate to your interactions with other players. So you get them as little rewards for leaving the Vault or the first time you kill a creature or the first time you pick fruits or vegetables from somewhere.
Here's the full Fallout 76 map. The push for continuous content being added could mean for potential multiplayer DLC expansions, or possibly something comparable to raids in Destiny. Bethesda's Pete Hines did mention earlier this year that they plan to support this game "until the end of time" but that's pretty hard to do without a solid reason to play. While the newest game in the series is pulling away from the traditional single-player open-world experience it's know for, game director Todd Howard has made it clear that future Fallout games will not follow the same format.
Hines concluded that it will take a lot of work but mods and private servers will be coming to Fallout 76!
Fallout 76 launches on November 14th for PC, PlayStation 4, and Xbox One.