I don't mean to be offensive, but my first though reading this was: "OK, someone just drunk the Web 2.0/Ajax/HTML5/GoogleOS kool-aid"
First of all, it's not like these ideas need to be evangelized anymore. Every geek on this planet already knows that HTML5 is "the future". In fact, the future is already here. Studies say that people spends 50% of their time using the web browser. A web browser is most of what Joe User needs these days. In one conference, Google said there hasn't been any killer desktop application for Windows since Gmail was released, and it's true. All the new things are being developed for the web.
We have seen all this in the past. In fact, Unix was developed with the "cloud" mindset. Unix shells were the 80-90's "web services". And clients didn't going away. Yes, there were "dumb terminals", but then Linux appeared and it became fun to run a unix client on a PC. The history's wheel isn't stopping on HTML5 and Google.
The problem for Fedora/Gnome isn't HTML5, it's Android. Android has become Google's desktop, development platform and distro. Where is my Gnome Mobile? Where is my KDE Mobile? Where is my Gnome Mobile App Store? Where is my Fedora Mobile distro for HTC devices? Yes, Gnome/KDE/Fedora are becoming irrelevant for end users, but only because end users are going mobile and there is not a KDE/Gnome/Fedora for mobile devices, only Android. That's what it needs to be fixed.