Then you keep the wheel. You still have two people covering your backs as you switch weapons. Or you use voice commands via Kinect or your headset, to switch them on the fly. And depending on the class, you'd be stuck with two weapons anyway. I haven't played ME3 in a while, but weren't everyone's weapons reduced? In ME1, everyone could basically carry, like what, 5 different weapons? In ME3, someone like Garrus only had a Sniper Rifle and Machine gun.
I'd have no issues with only being able to carry two weapons, as long as everyone gets to pick a different class and brings something different to the table. Not everyone needs to be the jack of all trades.