I've been reading a Fallout 3 wiki and turns out Bethesda and Obsidian are using alot of the already created stuff from the Fallout 3: Van Burren game that was never made. The legion, entire characters, and scenarios have been picked up so I guess in one way or another Van Burren is still being made. I'm waiting to see if future fallouts use more of the van burren material as there is a ton of unused stuff still.