It's basically a slow news day and any quasi-hippie article will make the front page....film at eleven
First off the cardboard case will have to find a moronic PS company to allow their power supply to be put inside a paper case if they want to enter the brick-and-mortar sales market. I can think of very few companies that would jump at that idea to be quite honest since it's pretty fucking stupid. I know corrugated carboard, but I wouldn't put my $700 GPU and quad CPU's in it to appear to care more about the environment. In reality the case isn't the problem, but more of the poisons used in the manufacturing (and lack of common disposal) process that wind up in our dumps, instead of approved facilities.
Put a heavy corrugated box in a hot ass garage during a Texas or Arizona summer, then chat with me about the longevity of even high-end cardboard. I specifically am referencing very highend optical router boxes from Cisco/Juniper that I have in my garage, which are breaking down after a few months. Water as we know enjoys PAPER, which isn't normally a problem unless you are a fucking moron and put your computer parts INTO THE BOX. Since you apparently think it's odd to put a coating on something to improve the fire resistance (and subsequently water resists) I must say, you must be a raging moron. If you are running on ten years hardware, then sure I can see your point that the case storing your assorted drivel shouldn't be fire or water tight since a random short will always cause a fire, so will the bumped glass of -your favorite beverage-.
All of this under the concept that a paper case is much better than a metal one. Both are recyclable, but one is more resilient and a more practical solution. In fact the de facto metal one exists because it has a place, whereas a paper case is a problem looking for a solution.