Adobe surprise at this year's CeBIT, with the announcement of the Flash CS5 (project name) will support WebGL.
It is then possible complex Flash content, publishing as WebGL (.Html) to. So you need to plug the display in the future, no Flash player in more.
When Unity3D makes it too? can Unity3D soon as WebGL Publish(.html)?
so it's not possible to create complex web based games on the web with webGL. it's not only unity that don't want and can not do that. vision engine is creating a browser plugin for themselves but nobody don't talk about webGL. torque3D don't have any plan to support webGL and even the adobe will not create a director with webGL. there is another question in this topic with an answer from unity staff. http://answers.unity3d.com/questions/4894/will-unity3d-support-webgl oh as i see that question is asked by yourself so why should you ask a question like this.
unity is a different platform compared to flash. you might ask microsoft to support it for silverlight. they will not do that and even adobe will continue it's flash player for more complex flash RIAs.
Then again, there's this J3D: http://www.everyday3d.com/
It's not a Unity Engine per se, but it lets you export Unity scenes to webgl so you can at least look at them.