Flash was not always Adobe's property, they certainly didn't invent it, not that it was ever very novel in any way - but it's been a very fun
toy, albeit deeply deprived of computationally power.
Adobe has always produced high quality products in my oppinion but when it comes to Flash they've played protectionist and not been sufficiently innovative, aggressive or both - not to say open. And that's not good for a closed platform when things like
Silverlight, HTML 5 and orders of magnitude faster browsers happen to you.
This may be good news for Microsoft and Silverlight or it may be bad news (people being more wary of adopting proprietary technologies, especially when The Prophet has spoken and acted) but at least there is Moonlight as secondary and open "implementation
of" Silverlight. And Microsoft is also betting on both horses now (Silverlight + HTML and friends)...
There will come a time when the Web stack will have to be refactored and depending on how advanced Silverlight et al are at the time and whether Microsoft has committed itself to open-sourcing it or move to standardization, it might be a strong contender,
unless technological evolution has moved us to more radical paradigms at that time.
I disagree with your assessment that Flash wasn't very very novel:
Flash brought professional-level animation to the masses. It democratised vector animation and significantly flattened the learning (and effort) curves.
Lots of us will remember how Java applets were used from the mid-1990s onwards for things like in-browser games and scientific demonstrations, often crudely made because Java Applets are for programmers, not designers. Flash flipped the tables around and
made it easy to make a polished impression: hundreds of thousands of Flash games, videos, and animations undoubtably changed the web for the better.
Then in 2002 Flash 6 came out with support for video, thus marking the beginning of the end for plugin-video handlers: we all remember horrid experiences with the WMP control and QuickTime.
Flash has been innovating, but remember it's a product for designers, not developers. You won't hear them innovating on parallelisation or lambda expressions.