On the Acquia blog there's a recent post from Ryan Weaver from KnpLabs, well known for his contributions to the Symfony2 framework. In his post he suggests that the future of PHP is "shared power tools", less around the monolithic frameworks or installable software and more about the combinations of small pieces of code doing exactly what they need and nothing more.

[Things like Drupal, Joomla and WordPress are] painstakingly thought about and solved the same problems from scratch. And despite that, the results were incredible. How? Because they leveraged the sheer size and passion of their respective PHP communities. But it makes me wonder: what crazy things could we build if we worked together? Fortunately, we're on our way to finding that out. The PHP world is transforming and the individual armies and empires are blurring together.

He talks about how PHP developers should stop fighting the same battles and start working together using existing libraries to solve problems. He points out that applications, even the big names, are becoming more and more modular. Even Drupal has recently made the move to include Symfony packages for some of its functionality (other examples are given too). He also talks about "developer experience" in using these tools, what Symfony is doing to help it and how building on these and other components is essentially "standing on the shoulders of giants" to solve problems easier, faster and with better quality code.