Built in replacement player for flash content
Feature I would love to see in a web browser. A built in replacement player for adobe flash content. Since Adobe has no interest in making a player that actually works, like not crashing the browser (or the whole computer), sucking up all the memory (and still delivering choppy content) and isn't full of security holes. Of course if content providers would just dump flash content that would solve it. But that isn't happening anytime soon.
There are at least two open-source projects that implement Flash to some degree (Lightspark and gnash). Writing a fully-featured replacement is probably much harder than writing a web browser, because not only the specifications aren't public, but you also have to keep bug-for-bug compatibility with Adobe's implementation, so don't expect anybody to take up that task.
Both Lightspark & Gnash are stall project. For many years it stuck to support only Flash 6~9 plus partial support of Flash 10~11. And only support only 2/3 of Actionscript.
Mozilla attempt with Shum become only laughing stock. Not because it try to replace Flash, but because it got same fate.
Exclude security & performance problem. In ability, Flash is far superior. People not just use it for deliver Video you know.
From Adobe side they're more lean to Adobe Air to solve the mentioned problem.
HTML5 is opensource but brought new problems. Just wonder around these forum you'll see what people ask to counter it.
Making an at least on par replacement seem a major PITA. There some other projects I believe, they just out right dead.
Multimedia is really a different kind of beast. You'll need super big support (not just programmers) to even just to maintain it.