Adobe abandonment of Flex has to be one of the most perplexing acts of corporate self harm I have witnessed ( and been affected by). Dominating the Rich Internet Application space and poised to storm corporate apps by levaraging all those Flex Devs via Adobe Air and they... just knife them all in the back and abandon Flex totally. Just jaw dropping. Inexplicable.
Flex is now an Apache open source project. It still has an active developer community, some of whom are Adobe employees, and appear to work on Flex full-time.
Unfortunately, it seems the developer community is focusing most of their efforts on FlexJS, an HTML/JavaScript version of Flex. I could be wrong, but I don't see them making a very big splash in the crowded JS app framework space.