Even with PHP7, PHP still feels like it is playing catch up. There is nothing new or revolutionary in PHP7, just adopting features present in other major languages. Adopting as other newer languages like Go and Rust seems to be moving beyond those features. A catch up into a world that's on its way out, if one will feel so blunt. PHP's raison d'être remains its ease of getting an instance running on a webserver. But…
I don't think fewer people self-host. There are some going to big clouds, there are some using integrated offerings like squarespace, but there are still many hosting their website with a regular hoster. And probably in total many more than in the past.
> And even for those who do self-host, the advantage is becoming narrower as other languages have made it easier to distribute their web applications.
Did they? How?
With PHP, all the users has to do is to fetch the project files and upload them with FTP to the directory the hoster told them to. No other environment matches that - and no other environment is supported by those hosters. If you want to run something else - like Ruby, which I prefer to use, or something that creates a binary for you - you are looking at a completely different type of hosting. Digitalocean, Heroku - and that's not as easy, if the application is not provided as a one-click-install.