The challenge is in determining who is about to become obsolete and that is not clear. For example OOP remains the most popular and requested programming paradigm even though it has gradually slid into functional obsolescence more than a decade ago[1].

Even still legacy code will remain in use and talent to maintain legacy systems will remain in demand. My university still teaches COBOL because there still exists demand for people to maintain these legacy applications even if new applications are no longer written in that language.

[1] https://github.com/prettydiff/wisdom/blob/master/Object_Orie...