Screwed by the Network: The game likely would have been officially released as Fallout 3note although it would've technically been the 4th game due to the existence of Tactics, it would've been the 3rd official game had it not been for Fallout: Brotherhood of Steel - Interplay took sucha liking to that game (probably due to being a consoles' exclusive, more accessible game for the masses) that they delayed Van Buren in favor of making that game. Fans were outraged, and Interplay decided to rub more salt in the wound by not only outright canceling Van Buren (According to Word of Dante, due to budget contraints and a lost of faith on CRPGs due to the popularity of consoles at the time), but also deciding to make a second Brotherhood of Steel game. Of course, Interplay paid for this due to the first BoS game selling very poorly and Interplay going bankrupt.
What Could Have Been: Leaked design documents, screenshots, videos, and playable demos indicate that Van Buren would have probably been really, really good if it was ever actually released, which is, of course, never going to happen. Although many elements planned for this game were later used in Fallout: New Vegas, granting some vindication to the project.