Wiping the <LOL> off your face
You clearly haven't even bothered to look into how web pages work beyond Flash, but here's some info anyway.
"Experience tells me that embedded font rendering is a major reason why most brands choose Flash for interactive media, because they can't use the relevant branded fonts in other solutions - it looks crap."
"The latest Flash Player even moves into dynamic typographical layout territory and makes use of overflow text boxes, something that you'll see in Quark Xpress, Illustrator and Indesign."
The latest Flash player uses Webkit to render all that stuff. It's practically Safari with a load of plugins and scripting libraries. So, anything Flash can do, Safari can do. And so can any other browser. Opera can rotate text and skew it and do all sorts of stuff.
"handle tween animation?"
CSS3 transformations. I use them and they look nice in Opera, Safari and Firefox.
"handle in-stream video metadata?"
To do what? HTML5 browsers have in-built players that read the meta data.
"Hardware 3D acceleration?"
"Real-Time text effects, e.g. glows, drop shadows etc."
Old news. CSS does these already. I've been using box and text shadows for a couple of years now.
"Easily fill a screen with content irrespective of its "design size""
But that's how HTML has always worked. It's only when someone starts specifying absolute widths that you run into problems. CSS has rules to cope with different screen sizes, aspect radios, portrait or landscape, units for setting text sizes, line heights or boxes based on the width or height of the viewport, and a whole lot more. And then there are browser features such as zooming and fit-to-width.
"Interface with external devices, e.g. webcam streams etc."
Yes? All covered by the HTML5 'devices' spec. You really do need to look into these things before preaching and LOLing from your porch rockingchair in Hicksville.
And just wait until you see what the <canvas> element does! You'll feel like a flat Earther being told the world is round!