[astrodust]

For an application with no exposure, arguably it is.

When you upgrade to PHP 5.6 and your application grinds to a halt because mysql_query isn't available, you'll be wishing you'd fixed it sooner.

[zapt02]

If you're on RHEL/CentOS, 2023 is gonna be a bad year.

(RHEL/CentOS is currently on PHP 5.3 and will stay there for a long time.)