As someone that has worked around and with flash for years, I say good riddance. Though there are portions of the flash 'product' I think are much stronger than HTML5 and javascript (specifically, I feel that actionscript 3 is lightyears ahead of javascript), Flex was always one of the weaker parts. It always came off as half baked and did not blend well with everything else. The whole concept of MXML files was ridiculously obtuse and only led to unmaintainable code.