I get it. In a growing mobile environment ESRI (and hopefully everyone else) wants to see development focus on tools and technology that will include more users rather than exclude. Flash/Flex has been highly restrictive in this nature.
I remember reading something recently about ADOBE eventually planning on retiring the SWF as well, moving to a fully HTML5-interactive Flash/Flex environment. I get the feeling they'll try to make the IDE the same but the output is HTML5 compliant versus SWF files. *shrugs*
Either way, I'm kinda relieved. I've been trying to re-learn the new Flex (been about 6 years since I last coded for Flex) and I'm just not having time. Javascript is something I have more recent experience with so now I just gotta get up to speed with Dojo.
It'll be interesting either way.