I know the tv guide is in a 'coming soon' state and has been for quite some time. What I feel is even more important is channel hoping once your watching a selected channel. I am sure people have seen how Plex does this (top bar when you pull down)...however I feel the best DVR I have seen so far on Apple TV that set's a standard the Emby app would do well to emulate is that of FuboTV.
Instead of bolting the now playing channels into the top bar, they allow them to be shown in the bottom bar by pushing up on the siri remote..in addition they allow a long press to navigate back to the previously tuned channels.
Here's a couple of screenshots from FuboTV showing what I mean (note also the info panel is full screen and far more readable than what is currently on the latest Apple TV version).