It still works. I’m trying it out now. You have to wirelessly connect your PS4 controller to the system and select a profile. After that, start USF4 and when the game loads plug in your PS3 stick and it works. I’m doing this on a Hori RAP KAI. If you are following these instructions and it still isn’t working then plug your stick to your PC and go to Control Panel -> Setup USB game controller and if you don’t see your stick there, then something is wrong with your USB cable.