ok... I have an idea that probably wont be implemented because its too technical, but I can dream!
In a DLC involving Mother ship Zeta, or the Capital wasteland, one of the Bosses/Encounters you have to face is your Character from the 3rd Fallout game.
The Catch - the Boss is Generated off your Save File in fallout 3, based off his choices he has done - your Chars Gender, facial Dynamics, Perks, Choices, and Current Inventory
Heres the Catch - if you Bring Dog Meat to fight him/her, you have to make a Charisma check with Dog meat to keep him by your side.
I like this idea because I really want to face off against my fallout 3 Character Flynn, a Monster of a Man, maxed out in all stats, who also burns and eats people in Power armor.