One thing I'm absolutely hoping for in Fallout 4 is the ability to dual wield. Nothing would make me happier than walking up to some junkie merchant theif, smashing their face in with brass knuckles, and then blowing their brains out with a pistol. If we could mix certain guns/energy weapons with a one handed melee weapon, I do believe it could work if there was a special button for melee attacks only. Think COD, one smash of the right stick makes your character throw a punch or swing a blade with their melee weapon, while pulling the left trigger makes him ADS with his gun or energy weapon. Now that would be a magnificent change.
Edit: think of the possibilities with two handed weapons? You could beat down somebody with the butt of your rifle, conserving ammo,
And making them yield to you. If you're in a close quarters area you can sneak up behind someone and knock them unconscious without having to kill them. Of course with fallout I can see them adding some catastrophic failures where you accidentally kill some people, or hit them too lightly.