RTSP Streaming Protocol Support
The video surveillance industry relies heavily on the RTSP protocol (as implemented by ffmpeg, vlc media player, live555, etc) for streaming h264 and h265 video content.
It's not a new protocol by any stretch but it is part of the ONVIF standard that essentially all video surveillance manufacturers use as well as part of the PSIA standard which a subset of the manufacturers also support (in addition to ONVIF).
It's a simple protocol and there are plenty of open source implementations.
HTML5 does not include equivalent functionality.
WebRTC pushes VP8/9 and while it may support h264 it's often online baseline h264.
Other concerns: The video surveillance industry is starting to move to h265. Google and Mozilla seem reluctant to go there.
In my opinion it's an under-served industry and easy market share if you want it. It would also be beneficial for building UWP apps if RTSP and H264 (and H265 if possible) just worked for video elements.
RTSP is one of the most important piece in the interoperability puzzle. Interoperability on streaming media systems is tough because there are many related components (Players, Servers, Encoders/Tools) that you must share common mechanisms. Encoders and content-creation tools must be able to store content in files that servers can read.