I tested the Base64 thing with GPT4 and it produces code that does seem to work. There have been other tasks I've given it (C++, Clojure, JS) that it doesn't get on the first try or in some cases doesn't get at all though. One task I tried in C++ it kept going in circles and ignoring requirements from prior prompts and I tried numerous ways to prompt it.

All that in mind, I'd be lying to say I'm not more than a little concerned with the progress from 3.5 -> 4. I'm only two years into my career and my fingers are crossed that it won't significantly impact the market for devs for as long as possible.