But that's my point, H.265 will never make it to your SSP. H.264 never leaves the BD player or video streamer today. So you don't switch H.265, you don't pass H.265, and you won't ever see H.265 on a video processor spec sheet. I think people get confused because they see H.265 on TV spec sheets, but that's only for the TVs internal apps (streaming/Netflix/USB/etc). H.265 is a video compression codec, not a video format, and HDMI does not pass compressed video. Video is not like audio, there is no "bitstream" option that passes the compressed video over HDMI, so what codecs get used for 4K (or any) video (H.265, VP9, whatever) are irrelevant to the AVR/SSP/Video Processor.
But you're right about the rest though, Anthem's don't support HDMI 2.0 and can't pass 4K video. At least I assume no, but has anyone tried 4K24 via "through", that should work with HDMI 1.4.