In 10+ years of professional PHP development, the only time I've ever had to fix a codebase while updating the PHP version was when mcrypt was deprecated, and it was only around half an hour of work to replace it with a modern equivalent, including the time to re-encrypt the data.
Meanwhile, I've had the misfortune of inheriting a React application that would no longer build a mere six months after the original developer left the company. I've come to loath working on React projects due to the insane amount of library and tooling churn in that ecosystem.
That was in 2015, and it barely impacted anything I touched. So, granted, technically not quite 10+ years, but you get worse churn in JS frameworks over an 8 months period. (Unless it's jquery.)
