PHP, on the other hand, seems to have been in a decline which has finally levelled out.

https://www.google.com/trends/explore#q=nodejs%2C%20php&cmpt...

Note that this is on the same scale as node, which is no longer visible hugging the x-axis...

But is that a lagging indicator? Peak manpower for a successful project comes well after a project starts. Node.js was hip a couple of years ago, and lots of projects got started using it, so it wouldn't be surprising if lots of people are being exposed to Node because they've been added to these projects. In the HN echo chamber, hip projects have moved on to Go micro-services. Outside the HN echo chamber, Rails is still hip.

Wow, I did not realize the difference in search volume of PHP vs nodejs.