As the article mentions, this is a port of the previously-Chrome-only NaCL-powered version of Google Earth.
I doubt the web-based versions (whether JS/WebAssembly/Nacl, etc) will ever have the feature-set of the standalone Google Earth (nor is there much monetary reason for Google to do so).
I doubt the web-based versions (whether JS/WebAssembly/Nacl, etc) will ever have the feature-set of the standalone Google Earth (nor is there much monetary reason for Google to do so).