Indeed , to cushion the few year long decay it seems that CS6 will have the option to convert Flash to HTML5 & JS allowing for a smooth transition . There is already some experimental software for that . If the trend continues Flash will remain only a program for creating HTML5 / JS apps and animations .
I use CSS 3 with media selectors in every project, and have for the past year or so - it's nothing so different if you're used to the web standards, indeed it's a logical progression which has been around for years already.