How should educators ensure their curriculum remains relevant over time?
As a wise man once said, "We are preparing students to solve problems that don't exist / using technologies that haven't been invented."

I agree with alephzero in the sense that you can't avoid this issue.  Every sign is that technologies will keep changing rapidly, at least for the foreseeable future.

This is why we must always keep our instruction oriented towards concepts, not languages.  The syntaxes for arrays and lists will differ in different languages, but the trade-offs between the two remain the same.

One easy way to keep the emphasis on the conceptual is to utilize more than one language.  Over the first 3 years of our major, all students work in Python, Java, C, 6502 Assembly, and Scheme.  Additional languages are used for electives, depending on the nature of the course content.  By providing a more varied exposure, students can easily come to differentiate the underlying concepts from the syntaxes of the languages they are learning.