It would be incredibly easy to bring back dual wield and also make the single handed weapons useful on their own.
Simply halving the aim assist when you have two guns in your hand would be enough. No need to weaken the damage output, decrease accuracy, or add recoil. Dual wield would become this utterly powerful mechanic that people could utilize correctly if they aim their cursor. You could still spray with two SMGs, have a Plasma Pistol and a Magnum, Mauler and Spiker, all that jazz. But people will become more impressed because you really had to aim it. It would be a new meta for players to grind, and casuals could still enjoy it.