"Is Media 100 being updated?" is a good standalone question on its own, we'd all like to know, =).
"Is Media 100 being updated for a post-QuickTime Mac future?" - I assume the post Quicktime version, will be the same as the 64-bit version we're all crossing our fingers for, and there have been hints might emerge if there's sufficient demand for it.
Additionally, some people argued, despite Quicktime being abandoned in favour of AV Foundation (which has already happened btw), Quicktime would likely stay around for some considerable time, even if just as legacy software: https://www.facebook.com/groups/Media100Suite/permalink/1024153774280792/
"Philip Hodgetts thinks classic Quicktime will be around for a couple more OS revisions, Piers Goodhew thinks it could be around for another ten years! Steve Oakley meanwhile, is advising Media100 users start converting legacy videos to modern formats. It's a lively side discussion in the H.264 thread over on the IMUG: http://media-motion.tv:8100/Lists/IMUG-List/Message/82729.html "