My guess is no. Without compelling applications (streaming video did this for Flash), people won’t install O3D and developers won’t develop for it. It’s the classic cold start problem. In fact, Google would be smart to use O3D to provide better video playback for YouTube to drive adoption.
Meanwhile, some very smart approaches, like Unity3D, which uses C# plugins to provide sandbox security for unknown code, do as good or better job at the same idea. Unity has its own integrated WSIWYG editor, web packaging systems for multiple OSes, and comes with professional support. Other approaches, like Vivaty (also a browser native rendering plug-in) keep alive the last major attempt at Web 3D standardization, X3D, which was born VRML, Cosmo, and SGI Inventor before that. Some ideas never die.
The shining star in all this is the Mozilla and Opera efforts at adding native 3D canvas support. You see, if there’s no plug-in, then there’s nothing to install. Web pages could leverage 3D content as long as people are running a recent browser. But these approaches are not entirely compatible and it’s been slow going. Khronos is also trying to get OpenGL ES in browsers, which again could do well if it’s adopted, chicken and egg.
The problem isn’t that there isn’t one common language for 3D, or that it doesn’t run in a browser. The problem is human nature, and very few of these efforts seem to be designing for the real world.