I don't want to see the old Games Workshop approach to the game. I don't want to buy two starter sets, a rule book, a codex and a campaign book per faction. It would be nice to have a universal rule book that applies to all factions in regards to how unit types move and act with all the weapon and armour statistics included in it.
Just to throw something off-the-wall in, I'd like to see a later supplement that merges in the factions and creatures from "Wasteland". :)
I wasn't talking about mixing Fallout factions and creatures in the same army though, I was joking about having factions and creatures from a different (though spiritually related) franchise. So the Desert Rangers, the cyborgs of Base Cochise, the Guardians of the Old Order, the Servants of the Mushroom Cloud, etc. Not that it wouldn't be to hard to represent many of these with actual Fallout factions of course...
Link about Wasteland from the Fallout Wiki
Nothing screams Fallout so much as those two suits and T-45d.