I have to say, working with Houdini every day had me develop a particular hate for node workflows.
Not everything has to be procedural or visual, in fact there are a lot of scenarios when it is counter productive.
Having said that, one area where I appreciate it is when creating/editing shaders.
Is there any plan for something like this especially with 3D being an area of focus soon?
It is not planned no. Do you know if there are good tools out there that specialize in this?
Instead of asking for the implementation of visual shaders, I think it would be better to correct the method of creating shaders in defold, the application of shaders is complex and you don’t work with them live!.
In other words, you don’t look at what you’re doing if you don’t run the rendering!.
After that, they could evolve into the application of visual shaders, as their application involves looking at what you do.
P.S. It’s just my opinion. 
The first thing I did when I discovered defold was to research the use of shaders and I got this result. 
This is true, we do not really preview shaders in the editor (we do kind of). What I find useful is to run my project with the shader active and then use modify + hot-reload loop to immediately see the changes I make to my shader in the running engine.
Wow, those are some nice results!