But I think the movement is significant and can't be overstated. And recent developments are really even making it more and more interesting.
Now this is all well and alpha-geeky, but there are showing up the first "real-world" success stories: Voxer, Walmart, LinkedIn ...
Of course there are the critics.
Microsoft was pushing node.js onto the the Windows environment.
Now they are pushing it into their Azure cloud platform. And evolving a 3rd party ecosystem around that.
Developing for the desktop (or tablet) will most likely always be pretty different than for the web. For Metro style apps there will be a lot of new concepts, libraries and tools that are different to the ones that are used in web development (just have a look at WinRT, WinJS ...).
Of course another interesting thing will be to see how Metro style apps will change the architecture of future desktop applications. I think some concepts from web development will get adopted into desktop development. A stricter enforcement of separation between UI- and backend-components within a single application will most probably be a result (i.e. there seems to be no notion of traditional data-access in WinRT).