It's obviously a bit late to expect Bethesda to add anything major to the core game. But I believe Bethesda said that they generally start working on DLC as soon as the core games are released.
So now is as good a time as any to offer up your hopes and ideas. What do you want to see in the DLCs?
Me personally, I'm hoping to see something heavily inspired by Mad Max: Fury Road. Raiders have always been little more than a nuisance in the Fallout games... never a primary threat. But imagine not a gang... but an entire ARMY of raiders looking to violate the wasteland with the aid of new drugs created in the Mojave. Drugs like Slasher, Rocket, Turbo, and perhaps even FEV syringes.