I can see it now, you could play the Brotherhood of Steel or the Enclave faction, and there would be independent characters like smugglers and scavengers and raiders that could be thrown into the mix. Ghouls would need their own faction, but sentient ghouls would be like the independents because they would be able to play with or against the "feral" ghouls, but "ferals" would only be able to be on teams where all of the characters were ghouls. Super Mutants would need their own faction, obviously, and robots would be laregly independent.
And outside of a miniatures game, it would just be nice to have a set of post-apocalyptic minis for our tabletop RPG.