The new Material Design announced at Google I/O is supposedly an ambitious cross-platform design language that spans not only Android devices, but also the web.
Anything that is this ambitious should be treated with a healthy grain of salt. Let’s verify what Google means by cross-platform.
Android version compatibility
Given the severe OS version fragmentation of the Android platform, it is important to understand the entirety of version compatibility for Material Design.
Unfortunately, I could not find resources on the web that gave me a good comprehensive idea. I think Material Design will only be supported on Android L. There appear to be some support libraries that will make it easier to support older versions and a Material Design version with the same code, but it looks like that will be it.
Google does provide details of browser compatibility for Material Design on the web (the Polymer project). Unfortunately, it doesn’t look too good. According to this discussion on the web, Google is not taking browser compatibility very seriously.
In terms of compatibility, it is simply not up to the standards that most web developers would regard as sufficient.
The lack of Android version compatibility is understandable and will not present an issue. It will be adopted over time.
The issue is with Browser compatibility. Although impressive, there are many similar projects to bring a nice UI to web apps, and none are as restrictive in compatibility as Material Design. Web developers can simply chose one of these. There is little reason to believe that web developers will slowly adopt Material Design.
It’s still very much a research project.