This just won't ever happen. The people that wanted to drop PHP for something else (Ruby, etc) largely did so years ago. The hosting/running situation for PHP is just too basic and easy for people to get in to vs having to 'run a server' (Rails, etc).
PHP is still the only language that assumes HTML output by default. Put a file on a web server, hit it via a URL, and get HTML output. It's that simple. You can start at 'simple' then graduate up to complex stuff like Symfony if/when you want to. Every other language or platform forces a lot of extraneous concepts on you on day one, which is always going to be a turn-off for a not-insignificant portion of the people coming in to the field.