I shelved it a long time ago and never looked back. A couple days ago I rummaged through some drawers and there it was. Since I am happy with the TV app I wonder if there is anything else I could use it for. Probably not, right?
You can use a 3rd gen as a HomeKit controller to be able to access HomeKit items when you are away from the network if you don’t already have a newer Apple TV or a HomePod (or an iPad that always stays home iirc.) At least for now (who knows if Apple will deprecate it though.) That’s the one thing I can think of.
I think some of its streaming apps still work (sadly, YouTube no longer does). But you’ve already got an alternate solution in place.
If you think it would be useful, you can still use it as an AirPlay receiver, letting you mirror a mobile device to a TV.
I use mine as an AirPlay receiver for an audio receiver. The only time that gets tricky is when I need to access it for one reason or other, but I have a small portable Sony LCD I can plug into the receiver temporarily so I can see what I’m doing.
Actually, there’s one thing that 3rd gen Apple TVs can do much better than later models (Apple TV HD (Rev 4) and later): slideshows.
Rev 3s allowed a greater variety of ways to display the slides; and more importantly, let you associate specific iTunes playlists with a slideshow. (Note: when I’ve done this, I’ve been accessing photos and music from my iMac via iTunes using the Home Sharing option.) I’ve kept my AppleTV rev3 around for this reason. (I use my AppleTV 4K for everything else.)
From what I’ve read, this expanded slideshow functionality was lost after Apple TV HD (Rev4) switched to tvOS; some of the underlying APIs in the iOS variant used for Rev3 weren’t migrated to tvOS. However, no idea if that’s true or not.
PS Surprised to say I’m still getting firmware updates for the Rev3. Just got the “new firmware” notice for the Rev3 a few days ago.
Thanks for all the comments. It seems the Apple TV offers solutions to problems I have not been thinking about