Good. I do not want open source to prevail. I want free software. On a less provocative note, I don't understand the argument about web apps. There's tons of FOSS web application frameworks and widget toolkits, and the web is slowly conquering the desktop, for better or for worse. Has it not dominated?
Yes in term of lob/100 page "fairly large" form apps, No in term of native apps that actually do something.
When people show me a Photoshop,Indesign,Final Cut or a 3ds Max (fully featured,not just 3 edit tools hanging around) built in HTML,that work OFFLINE,that can open gigabytes of datas, with great performances on low end hardware, i will agree ( Which my old macbook does with no problem with these native apps).
Let's just take the many text editors built in HTML/JS , try to open a 10/15 mb text file(an apache log file for instance),execute a search/replace with it and see how it performs.
HTML everything is a promise, an idea that can be only fulfilled if the browser engines(not just the javascript engines,the DOM is not javascript) are as fast as native os(and hardware becomes faster too). That's not the case today. So people can say javascript 'is fast' all they want,that's not the bottleneck anymore.