My guess is that the flash tool-chain will be a lasting reason that it won't get instantly replaced by any of these new frameworks. There are a ton of developers and designers out there that know how to build flash and don't want to start learning new tools in unproven frameworks.

That said, I think the more and more bloated nature of adobe's tools will become a huge weakness. Developers will be able to build tools for much more specific work-flows that feed directly into specific use cases. Sproutcore and this one seem to be aimed at the 'desktop feel' app development for html5, I'm guessing there will be other frameworks and tools for creating games, vector animations, silly interactive websites, etc. Each of tho uses should grow it's own tool/framework specific for the task