I’ve summarized the main points of the Esri RoadMap for Web Developers below.
4. Flex and Silverlight will not be updated to version 4 so 3D visualization, enhanced vector rendering, stream layers will not be added to these APIs.
5. Flex and Silverlight APIs will not be deprecated….yet! I think it’s coming though so get prepared now.
6. One or two more Flex and Silverlight maintenance releases in 2014. Tech support will continue beyond 2014 but I personally don’t expect to see new releases after this year. The writing is on the wall for Flex and Silverlight.