I wonder if removing watermarks from images would be something a machine learning algorithm would be well suited for. Admittedly my understanding of machine learning is rather limited, but it seems like it'd be pretty easy to generate a large training set of watermarked and unwatermarked images for the algorithm to train on. No idea how effective it'd be though.
If you read the blog post, they link to their own research that does exactly that.
My assumption is that a deep learning algorithm trained on multiple different styles and variations of watermarked images would be much more robust to the sort of changes Google proposed in this blog post as a way to defeat their existing algorithms.