Apple just unveiled a system update for supported Apple TV, and it's definitely worth the wait.
A company representative at the WWDC 2018 presentation began talking about Apple TV 4K and that iTunes supports content for this model. In addition, it was announced that Apple TV 4K will receive Dolby Atmos support with better sound quality.
All supported Dolby Atmos movies and TV series will be updated for free. Apple did the same with 4K HDR content.