Shaders, and performance are the real meat of WebGl. Also if object rendering get's added. It would be really helpful to have WebGL for the better rendering. However, for the most part I'm pretty sure we can work around not having WebGL. While WiiU will probably not support WebGL, maybe the next iteration will.
Though I want to thank you for you working with Nintendo and Scirra for working to help open another platform for C2 games. You rock :)