Actually, I think a refresh of the Apple TV would be a great move on Apples part. With Apple TV+ and Apple Arcade both launching this holiday season, new hardware would certainly create some additional buzz around those services. They even could offer a bundle with a gaming controller and a free six month Apple Arcade subscription or something.
However, I don't think it will be a "next generation" kind of update, my guess would be a mid-cycle update like the XBox One S or PS4 Slim. If we look at the Geekbench results, Apple could easily replace the old and power hungry A10X with an A11 – this would achieve an even better performance, and it would allow the device to get rid of the fan, which could make it smaller and quieter. Also, the A11 could by now be cheaper to produce than the A10X.
However, I don't think it will be a "next generation" kind of update, my guess would be a mid-cycle update like the XBox One S or PS4 Slim. If we look at the Geekbench results, Apple could easily replace the old and power hungry A10X with an A11 – this would achieve an even better performance, and it would allow the device to get rid of the fan, which could make it smaller and quieter. Also, the A11 could by now be cheaper to produce than the A10X.