Interesting, write up and scenarios. I doubt the remains of the current generation will be found as intact as the ones you just wrote about. Checks out people of old had advanced ways of preserving than we do. Maybe that’s to be tested and found out by the next generation.
Who knows, only time can tell. Maybe some remains will love longer, but many are cremating their loved ones, so those stand no chance from the start and I've read about human composting as well, so I think this kind of burial have a good chance to disappear soon.