Reverse engineering, something tells me, that it’s gonna be a most useful skill for control system engineers for next 20 years.
Really, imagine all the systems made in last 30 years with no standards. I mean the standards for SCADA/HMI. Those standards were just actually developed in this period. And most of those systems developers are already retired. To make it more fun, the large systems are made and were changed by different developers with their own understanding of a good development.
So, when you get this system for support or modification, you can find, that you cannot find. You cannot find any actual documentation, you cannot find two identical structures in the system, you cannot find any following of a KISS paradigma.
And in worth case, nobody even knows a process should be controlled, and they ask you. They ask you, who suppose to be a very last cell in a chain as a SCADA/HMI developer!
Now, how many such systems we have today? IMHO – 99.99%
Good luck everybody.