Another nail in Flash coffin?

I'm not a techie so colleagues who teach computing at my university may disagree with me but the more I read about Flash and HTML5 the more it feels as though Flash is in permanent decline.  The quote from this GigaOm article about SoundCloud seems rather convincing:

"People are eight times as likely to share the sounds after playing them (with the) HTML5 widget as compared to the Flash version,”

With those metrics why wouldn't you migrate to HTML5?