The Fallout series is one of my favorite game series that I have played to date. That being said, I feel like it could benefit from adding some extra elements.
Co-Op
When players ask for multiplayer support for Fallout I sure hope it doesn't turn into a Skyrim: Online shin-dig, that's not the fallout way. What I DO want however, is a way to enjoy the game with a friend. It gets lonely in the commonwealth and making the game co-op would add an insane amount of replay value. The extra tactics that would be introduced is great.