"They're single-vendor solutions [and] they don't really fit well into the Web platform," Hickson says. "It's always a problem when you're stuck with a single software provider -- what if they decide to abandon the product you're using? What if they decide to start charging? With an open platform, there's no such risk, since we have true competition, many vendors, and an open standard that anyone can implement."
Hickson adds, "It would be a terrible step backward if humanity's major development platform [the Web] was controlled by a single vendor the way that previous platforms such as Windows have been."
Mozilla wants the Web to stay open and ensure that capabilities such as video are not beholden to corporate entities, says Firefox lead Vukicevic. But whether HTML 5 and Canvas displace Flash, Silverlight, and JavaFX "really depends on what developers do," he adds.
Lack of support for some HTML 5 technologies in the popular Internet Explorer is an issue for developers, says Vukicevic. "The fact that IE doesn't support a lot of these advanced features really holds back Web apps," because developers must instead do extra work such as supporting Microsoft-specific APIs or writing a portion of their application in Flash, he says.
The case for proprietary add-ons: They're better and available today
Although all three companies are involved with the W3C's HTML 5 efforts, Microsoft, Adobe, and Sun each defend the need for their technologies.
"HTML 5 is still a standard in progress and the makers of it say it will be five to ten years at least before it's done, so it's too early to make any comparisons at this time," a Microsoft spokesperson says. "Silverlight will still be necessary as it provides more advanced features -- such as a richer and faster programming model (C#), 3-D, and out-of-browser capabilities. With those features, Silverlight will ultimately provide a richer Internet experience."
"HTML 5 faces many challenges," says Dave Story, vice president of developer tools at Adobe. "The browser market remains highly fragmented, and incompatibilities between browsers reign. The HTML 5 timeline states that it will be at least a decade before the evolving HTML 5/CSS 3 efforts are finalized, and it remains to be seen what parts will be implemented consistently across all browsers. In the meantime, the Flash platform will continue to deliver a ubiquitous, consistent platform that enables ever richer, more engaging user experiences."
Sun vice president James Gosling, often considered the father of Java, says JavaFX "has much more advanced rendering, performance, and behavior than HTML 5."
Analyst Cote sees no immediate threat to these rich Internet app browser plug-ins: "It would take many years to reproduce the functionality in those plug-ins." And he expects the concept of plug-ins to continue to be useful when HTML 5 does ship.
Google's Fette agrees. HTML 5 is only a starting point, he says, and companies such as Google will add their own advancements, such as the ability to drag and drop images to a browser.
A few industry players may be conflicted
Most companies involved in the HTML 5 effort are browser developers or rich Internet application tool developers, but not both. The exception is Microsoft, which therefore is in a difficult situation, says Almaer. The company has heavy investments in trying to propel Silverlight to dominance. "That's a big elephant in the room for them because you can imagine the Silverlight team [whose] whole existence is to add [this] functionality in. [But] if Internet Explorer puts it already in there, why do we have Silverlight?" he asks.
Google may also face some touchy decisions. For example, its YouTube subsidiary uses Flash for its video, but the inclusion of HTML 5 capabilities in browsers might cause YouTube to rethink that decision, notes Fette. "It's a cost/benefit analysis that they'd need to make."