NVIDIA does say that it expects that most apps will resume 4K soon via coming server-side updates. Addressing apps that aren't streaming in 4K as they should isn't all the update is tackling. It also redesigns the volume UI for Android P. The update resolves occasional video playback issues, and bugs that were plaguing the IR volume control when accessibility features are enabled is fixed.
Users that had seen the error message "drive address format is not valid" message when connecting to NAS will be spared with the update. Also resolved are issues with a USB DAC that would set the audio volume too low after a reboot and an issue where sideloaded apps appeared as system apps is resolved. Storage issues with SD cards and internal storage are fixed. A "rare" Wi-Fi disconnect bug has been addressed and multiple updates for accessories were added to improve controller operation.
There are still some open issues not addressed in this update including HD audio drop out, YouTube 5.1 PCM not working, and issues with location services remain. It's worth noting that a couple of users on the NVIDIA forums have reported that the update failed on their devices. A wealth of other fixes was applied in the update, and all the fixes can be seen here.