You wont be jobless in a few years even if you continue writing PHP. So don't worry. The scare tactics are nothing but marketing usually. When Rails was initially marketed DHH used Java as a scapegoat. Ironically the Java stack traces he posted as proof in the early days of Rails have nothing on the monstrosities that exist in modern Rails apps.

I would recommend playing around with some other technology though, not so you can move to greener pastures but to just get a taste of what else is out there. Front-end stuff like Angular and Ember (which require some knowledge of HTML/CSS and JS, which as a PHP guy I bet you would have). Tools like these may slowly make backend technology less differentiated on the small to medium scale as time goes on, so you can't go wrong with investing time in frameworks like these.

Coming from PHP, and probably knowing some JS, have a bit of a look at Node (and Express, to get started), the concurrency model is different enough from PHP. Or even have a look at (gasp) ASP.NET MVC. I don't think that tech gets enough love these days. Try using Heroku with Rails and then go and try and use .NET with Azure. You'll be surprised at how much more responsive Azure is by comparison and you'll be enamored with the tight tool integration.

Either way, there's nothing to worry about. There'll still be heaps of PHP apps to maintain in your lifetime. It might make it harder for you to jump into some fancy new start up, but if you don't wear a cap backwards and have skinny jeans you wont get a job with the cool kids anyway.

Set aside a couple of hours a week to explore some alternatives and see how you feel within 3 months.