My C code from 15 years ago works fine, but code in other languages can end up breaking within a year. I've moved much of my development back to C++ just so I can have reasonable confidence my code will work when I come back to it in a couple of years.
I don't care if Python 2.7 never gains another feature, as long as my code will still work in Windows 13 and Mac OS X 10.17.
Conversely I'm always behind on Node as it's realllly annoying when a third-party lib breaks from an update. Larger packages will be fine but when you're dealing with say a Meteor package derived from an NPM package it's pretty shitty.
I'm probably in a special area -- algorithms research. I tend not to use many libraries, and I'm often taking code written 10-20 years ago and wanting to get it working. The code is often VERY complicated, and I don't really want to reimplement it.
Finally (and probably most importantly) I don't care about security holes, I'm not going to run this code on malicious input.
Would you want the world to still be using K&R C? Because I remember the transition from that to ANSI C, and the special macros to make function prototypes work across both languages. The Python transition is little different.