I am a little confused, it seems like you are proposing an interactive CUDA guide, but there is no mention of CUDA at all. Having spent a lot of time in graphics, I feel like better test environments for GPU programming will go a long way towards higher market adoption, it's a nightmare debugging sometimes
Shaders have there own stripped down C language to run on parts of the graphics pipeline as apposed to CUDA which is a much richer framework with a lot more control (and knowledge) of the GPU it's running on.
CUDA is an NVidia only GPU framework. Shaders are used in conjunction with graphics frameworks like OpenGL, DirectX(?) and WebGL.
The interactive nature is great. Normally shaders are a just a big string or file that gets submitted to the graphics card driver to get compiled and run on the GPU.