I think the point of the article is not the end truth of what he says, but just to encourage speculation, so I think all of us will draw different end conclusio

I think the point of the article is not the end truth of what he says, but just to encourage speculation, so I think all of us will draw different end conclusions. I doubt that we'll have as many iterations of society as he suggests. At some point we'll do something that kills all of us, and will then hand it off to the next species. If you look at Detroit, it doesn't take long for nature to take back buildings. I would just think that there are certain artifacts or clues that would be somehow visible. We are leaving much more artifacts than every civilization before us put together. But I might just be inserting my short term bias into the situation.