There have been good cheap options for TV boxes for quite a while (the Amlogic S905 was released in 2014). They were game changers back then.

That said, LibreElec has been beta testing the RPi5 and will support it. Dev images are ready: https://libreelec.tv/2023/09/28/rpi5-support/

The Pi4 can already play 4k24 HEVC. There isn't a lot of 4K video content with a higher frame rate.

Good point H265 support is badly needed these days