As much as it comes up, I don't see Apple making an actual television. 95% of the cost is the panel, which they don't make. They'd be buying panels from one of the established TV makers, in order to put them in a shiny Apple enclosure with an Apple TV glued inside. There's not a huge win there over just buying an LG or Sony TV and plugging an Apple TV into it. Also, the replacement cycles for the screen and the smarts are quite different. You might keep a really great screen for 5-10 years, while you're likely to want to upgrade the computer driving it (i.e. the Apple TV) more often.
On the other hand, a "HomePod Home Theater", where you get an Apple soundbar that could either be the front L/C/R channels, or could be the center channel while you use dedicated HomePods for the L/R channels (as well as the surrounds), could be an awesome setup. At this point they'd have a hard time prying me away from my Sonos setup (regardless of how much I like the Apple ecosystem), just because the Sonos gear is here, and works great, and was spendy. So they'd have to give me an incredibly compelling reason to replace it. But for a lot of other people, a HomePod Home Theater would be an awesome thing.