That's the mantra I'm hearing about HTML-5 full browser support, and without full browser support by the major players --including IE-- no serious website would ditch a universal (save for Apple's ludicrous position) format for HTML-5-only.
Seriously...every current user with a browser would have to update to something that supported HTML-5. As evidenced by the numbers of individuals still using IE6, that's no easy feat. So, this changeover is going to take awhile. We're still going to have flash around for some time to come.
I never would have guessed this would have happened as quickly as it did:
http://www.engadget.com/2010/04/01/netflix-ipad-app-now-available-in-the-app-store/
So now with Netflix, You Tube, ABC, CBS, Pandora, Last FM, the NYT, the WSJ (plus Hulu... as rumored by the WSJ) all changing their sites to support HTML 5 or producing native iPad apps, why exactly do we need flash again? Vimeo, maybe but with all the rest onboard how long before they follow suit. Other than the above listed use cases, I can;t think of a single use of flash that I actually care about.
I say good riddance to dancing monkey mortgage advertisements and bootyliscious splash pages for trendy restaurants and boutique hotels.

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