Bethesda’s Oblivion was so open-ended that the main story became insubstantial. Fallout 3 is no different. There are many sidequests to tackle, several of which have the ability to make the player forget about the main storyline. But when the game concludes, it literally concludes. There are no more opportunities to grab bobble heads or snatch Nuka Colas from dilapidated supermarkets.
Not at this time, no.There’s always the possibility, but it doesn’t sound like its going to be any time soon.