Google and platforms

So here’s my question: if Google replaces Windows with their web-based operating system, on what operating system will it run?

The answer is, well, Windows.

A computer needs graphics routines, networking, a window manager, UI toolkit, XML parser, HTML display, etc.—even Google’s desktop apps need these things. Web browsers certainly needs these things.

But “these things” are provided by Windows. (And Mac OS X, Linux, ZETA, etc.)

Dammit, Jim, I’m a developer, not an analyst. What is it that I don’t understand?