Fabien Potencier, founder and project lead of Symfony:
Symfony 4.0 will be released at the end of November 2017. During the next few weeks, I will publish articles about my ideas and the main changes I want to implement for Symfony 4.
So far 4 articles have been released by now, with more to follow:
Symfony 4: Compose your Applications →
Symfony 4: Monolith vs Micro →
Symfony 4: Best Practices →
Symfony 4: Directory Structure →