Really neat deep dive into a seemingly simple process. It talks about L-Systems, which are cool fractals built from very simple rules. The guy that made a map of reddit also made an L-System visualizer:
https://anvaka.github.io/lsystem/
L-Systems are named after one of the co-authors of a book called The Algorithmic Beauty of Plants, which is a deep dive into basically the math of plants. Very much changed how I look at plants.
I'm not sure they're predicting beyond where the US has already gone, just that other countries seem to be following the same trend. The trend shown can't continue in a linear fashion forever, and I don't think they'd argue that it's going down, so best guess at what they'd predict is that it will level off soon.