This question was made over 9 years ago. It made sense then, it doesn\'t make it now. Flash is hard on its way out; sup
There are many good points here, and like a Martial Arts fighting style, each point has its thrust, and each can be defended; but each can be defeated with the proper moves.
Anyone standing on arguments about "propietary" plugins will fall quickly. Microsoft, Apple, and Adobe all bear the guilt, but that's just BUSINESS. You won't change business overnight, and each layer of complexity added by a new tag such as
HTML 5 works now, and so does Flash. How it is implemented, the skill it requires- this defines each resource, whether it's an employee's performance, a webmaster's power, or a domain's influence.
Although I'm only 40, I began programming when orange or green monochrome monitors were the color choice, and hardware installation came with prayer books instead of instruction manuals. Maybe you could figure out AT commands for the modem when it wouldn't configure with your hardware, and 64K RAM was like, WOWWWWW!
HTML 5/Flash is a minor nuisance compared to that crap. Let's all learn how to collaborate in community toward a better resource. There is an Open Source Flash Project, it will have bugs. So will HTML 5...
Every argument here is true, but not necessarily productive. Use that energy toward a solution.