Guess we're all waiting for the Shinsen release.

Just watched episode 5, and it seems like there were some truths to all the theories here. Certainly there's a resources problem, but there's also some sort of disease being alluded to more directly, especially when we see Cassherns first casuality. But then we see that there are some parts that are still prestine (maybe because they haven't been exposed to the environment) that would enable these robots to get fixed.

So what I'm getting at is that there's certianly a resources problem, had there been resources around the robots would need not fear this ruin. Just the same there's some sort of supernatural thing or disease that is causing this corrosion of the environment to spread quicker.