PLC programming can be automated by an experienced human being who can think and reason and has the wisdom to understand the limits and what needs to be polished "by hand", but it is unlikely a field that can be replaced by a soulless algorithm.
Now, if you have a job that only requires talking to people via technology and mistakes are no big deal, I can see these advanced language models putting you out of work and rightfully so.
"Hey chatbot, write a program to operate this water plant."
"Hey Alexa, go feed the cows."
"Hey Siri, find out why the NC contacts on that actuator close position limit don't always seem to make a PLC input. Don't forget to padlock the hatch and leave the keys in the operators mailbox back at the maintenance shed when you're done."