This paper is amazing, and exactly what I was thinking of posting in response to that part of the article. The amount of research Deepmind is putting out is astonishing, and even if you are paying attention it's hard to keep up with it all. Here are just a few papers I've been looking at from the last few months, maybe none of them are advancements on the level of AlphaGo & Zero but they still show significant progress in a wide variety of areas.
And there are many others besides these, not to mention all the significant research being done by everyone else who isn't at Deepmind. The authors idea that interest and development of these topics is dying down or that Deepmind is running out of meaningful research to do just seems uninformed.