Gigabit Ethernet or 10 Gigabit Ethernet wiring for the house.
Gigabit Ethernet or 10 Gigabit Ethernet router and network switches.
10 Gigabit Ethernet might be an overkill... but 10 years from now... who knows... 4K HDR streaming may be the norm.
I'd personally focus on Gigabit Ethernet and/or 10 Gigabit Ethernet wireless streaming i.e. a strong router/repeater/network switch based network.
Everything is streaming these days. Goes for both audio and video.
Considering all content is wirelessly streamed from halfway around the world or a server based in another city - that approach works very well inside the home too.
The rest is very easy with devices like NVIDIA Shield, Chromecast, Roku, Amazon Fire TV, etc.
Invest in a good NAS like Synology and a backup like OMV to stream/store your own content and you are all set.