Vanilla will end PHP 5.6 support in 2018
Official support for PHP 5.6 ends 1 Jan 2019. Support for PHP 7.0 actually ends several weeks earlier than that.
We're announcing that support for PHP 5.6 in Vanilla ends with the new 2.5 release (and its subsequent patches).
Vanilla 2.6 (the next version, not yet announced) will require PHP 7.0 or higher.