Iain Poulson has published a thoughtful request on the Delicious Brains blog asking WordPress plugin developers to stop supporting legacy PHP versions. He covers some of the benefits of developing with newer versions of PHP, what Delicious Brains is doing with its plugins, and using the Requires Minimum PHP Version header in readme.txt.
While we wait for the Trac discussion to roll on and the WordPress development wheels to turn we can take action ourselves in our plugins to stop them working on installs that don’t meet our requirements.
We do this in our own plugins where it is strictly necessary (WP Offload S3 relies on the Amazon Web Services S3 SDK, which requires PHP 5.3.3+ and will we will move to PHP 5.5 in the future), and the more plugins that do this out of choice will help move the needle further.
Its main goal is to reduce the number of WordPress installs running on unsupported PHP versions through education, awareness, and tools to help users update their site's PHP versions.
This project is in need of contributors. If you're interested, join the #core-php channel on WordPress Slack. The team has meetings every Monday at 11:00 AM EDT. You can also follow the #core-php tag on the Make WordPress.org Core site where links to chat logs and meeting summaries are published.
Source: WP Tavern