I don't think a Fallout movie would satisfy in the sense that you don't have any good reference points for making a story that would truly be relevant. It sounds odd, but the appeal of Fallout, to me at least, is due to game being more about telling the story of a compelling setting rather than the story of the people living in it. Most, if not all, movies are purely character driven where to appreciate Fallout you need to dig into the background story in order for it not to become "just another post-apocalyptic" setting - it's the kitchy artwork, the dark humour and the entire ambience that makes Fallout what it is, not the story per-se. This is why a movie never would be truly capable of getting the right "feel" and become truly a Fallout product rather than a shallow IP revenue product, because there's not opportunity to explore the world yourself.
If it had to be done, I'd like seeing it done similar to what was done with with the Animatrix - a collection of animated short films fleshing out the background story of essential Fallout events. A couple of examples could be a recounting of the events leading to the war in a coherent account, the story of the founder of the Brotherhood of Steel, a tale of the Brotherhood of Steel migration from the West-coast to the East-coast (maybe the tale of the Scourge(?), where the then young Elder Lyons saved the children of a Wasteland village, adopting them into the Brotherhood), the tale of the first Vault Dweller, life in the Enclave... basically tales that'd flesh out the universe rather than a whole new story.
That's just my opinion though, as I'm pretty reserved about movies based on computergames - I don't think I've seen a single one actually capturing the essence of the game they were based upon, so [censored] the Fallout IP due to greed would be complete sacrilige in my eyes.