A lot of discussion about the demise of Flash is focused on how CSS and JavaScript can now create equally pretty-looking websites, which is fair enough. But take it from a long-time audio developer: HTML5 audio is essentially useless for creating web applications involving almost any kind of audio. Even Firefox, which has the best HTML5 support so far, offers absolutely nothing like what is possible using the combination of a Flash client and a dedicated streaming server.
Flash might have a lot of bad points (which I'd be the first to call out) but RTMP audio (which also handles both video and arbitrary data) really isn't its worst feature, and for this reason alone its going to be a significant part of the internet for many years to come.