I saw Atgames make a "pair of paddles" Atari 2600 controller to the "plug and play" lineup. They already have the proper molds and electronics to make them. Why not make a PS4/X1/NS controller from the same mold.
There’s even more option for the Switch.
1) Switch wheels already exists. They could be used instead of paddles for limited radius games like Pong, Warlords, etc.
2) Trackballs, Rollers, and Spinners can be used with a Joycon. Put a Joycon in a hamster ball for trackballs, and a cylinder for Major Havok, and a dial for Tempest add buttons, make it ambidextrous by making it flippable 180 degrees. Tempest 4K could use a Joycon Spinner.
3) I believe Sentinel was originally a Light Gun game, plus they could use 7800 light gun games, and other companies might want to make light gun games, and ever since they purged CRT TVs, there has no been an accurate light-gun substitute. The best one was the Wii Mote. But that was awful, (but other modern solutions are worse) because it a) had to be set up perfectly, and b) dididn’t know certain factors which would have made it more accurate. A simple, no-fuss-no-muss way to do it is to just take a picture of visible light. A "camera gun". None of this infrared stuff. The machine knows what’s on the screen. If it communicates with the gun, then it can use the picture to tell where the bullet goes. The calbiration can be used to adjust for light in the room. And the only way you can accurately compensate for the screen is to take a picture of the screen. It would understand position, scale, and rotation.
4) The paddles and the 5200 controller works because it’s non-self-centering. The only games where self centering works is "digital" arcade game conversions. Star Raiders, Missile Command, Kaboom, and Star Wars all worked better with a non-self-centering stick compared to a centering one. Warlords is tiring with the self-centering, except for the 2nd 360 version, because it wasn’t trying to be the original, but instead an update.