> Their problem is that people are going to want a single interface to view everything through.

I mostly agree with this. I know you're talking about a single streaming service, but just to expand your point, for me, my single interface is Roku. From it I can access Netflix, HBO, Amazon, Hulu, and a ton of others - all with the same remote on the same TV. One of my favorite permaculture Youtubers even has his own Roku app/channel. I've been looking into creating my own Roku app and the process doesn't seem overly burdensome. You need video content, an HLS or MPEG-DASH streaming webserver (I'll use nginx and HLS), some json, and maybe something minor I can't remember now.

But I like your idea of a standard streaming API. If it actually happened the resulting ecosystem would be awesome.