Fallout 4 developer Bethesda revealed something new about the game today on their Twitter account. People have been wondering if Fallout 4 had a specific ending point, and
the response was:
"To our fans who've asked: Fallout 4 doesn't end when the main story is over and there is no level cap. You can keep playing and leveling."
So if you want to, you can play Fallout 4 forever, or for as long as your console will last before it wears down, or as long as the Fallout 4 software remains compatible and playable on a modern PC. Or until you die, best-case scenario.
People were asking because it hasn't been allowed in the past. Fallout 3 had a definitive ending in its story, and because of this, the game would not let you continue beyond that point. Fallout: New Vegas stopped after a certain point as well. It was only until Fallout 3's third DLC pack, Broken Steel, that anyone was allowed to continue past the main story's ending.
Fallout 4 comes out for Xbox One, PS4, and PC on November 10.