There aren't many (any?) services that are offering Bluray quality 4K HDR streams but even those are only 140 mbps. I would think 1 gigabit down should cover most families handily, especially when you consider most streaming services are more like 20 mbps max.

The main argument I see is "if you build it they will come" i.e. we won't see higher bitrates until connections like these are more common, but for now gigabit has even fairly extreme use cases for video streaming pretty well covered.