Such an adapter can be beneficial only if you also have a means to wireless charge the phone as well (e.g., wireless charging pad)--otherwise it's more a gimmick product than anything else since you would still want/need to keep your phone charged while using this product. Unless you have a wireless charging pad in your vehicle, you'd have to connect your phone to USB to keep it charged, thus defeating the purpose of trying to have a cable-free solution to integrate your phone with your vehicle's multimedia system.
Also--unless that Bluetooth chip is capable of high audio quality streaming, you will lose some AQ when playing music via wireless CarPlay since it uses BT for the audio stream; I can hear the difference in AQ in my Optima when using the UVO to play music via BT vs. wired CarPlay. I could be wrong about the BT but most wireless car audio solutions I've seen all use BT to stream the audio wirelessly--I reckon the Wifi is used for the other CarPlay functions (e.g., phone, text messaging, Apple/Google maps, Contacts list, etc.).