The short_open_tag INI directive was not removed in PHP 5.4 and hasn't been removed to this day, even the bleeding edge PHP 7.0.0alpha2 has this INI directive available.

What happened in PHP 5.4.0 was that the short echo syntax (<?=) was decoupled from short_open_tag, so that the short echo syntax is always available regardless of what short_open_tag was configured as.

That being said, the advice is (as it has always been) to not use the short opening tag (<?) in your code for the simple reason that the code will not function when short_open_tag is turned off.