Just because Adobe and Microsoft are abandoning the Flash and Silverlight run time environments doesn't necessarily mean they're also abandoning their respective Dynamic Streaming and Smooth Streaming protocols. Being HTTP based I'd think it'd be a natural fit for an HTML5 video player in a browser to use these protocols.

In my experience the way the socket API can slow down a processor is having to monitor many thousands of socket descriptors using select() or poll(), like in a web server. For Linux epoll() was created for this scenario.