Dedication: A new fan-made DLC for Fallout 4 that's nearly two years in the making could be enough to hold diehards over until Fallout 76 arrives later this year. While there are still a few known bugs, it's otherwise a top-notch expansion like you'd expect from Bethesda.
Northern Springs is a land expansion for Fallout 4 that's said to be larger than both Far Harbor and Nuka World, official DLCs straight from Bethesda. It's located at the top left corner of the map and can be explored even if you don't tackle the main quest associated with it (do note, however, that one of the main characters will be hostile if you choose not to go through the main quest).
Northern Springs adds more than 25 quests, four fully functioning, voiced followers, three settlements, two player homes, new weapons and armor, four new jobs to choose from, new enemies and more. There are even random ghost sightings (remember the Vault-Tec salesman from the opening sequence? He's back!).
The mod's chief creator, jshrapnelc, notes that Northern Springs is both enormous and difficult. A character level of 40+ is recommended if you want to be able to hold your own in the new area.
If you're interested in giving Northern Springs a shot, head on over to Nexus Mods to pick up the requisite files.
Fallout 76 is scheduled for launch on November 14, 2018.