There never was an actual plan to bring these design to life in any official capacity, but artist Daniel Araya really demonstrated the potential for a CG Justice League with these designs. Here is what he had to say:
Just for fun I started doing concepts for a faux Justice League CG movie. I've always been a huge fan of Bruce Timm and the DC Timmverse he helped create, and I thought it would be cool to basically design the JLA movie that I would direct if given the chance. I didn't do any huge drastic changes because I didn't want to betray the characters in terms of who they are and what they're about.
See some of my favorites below.