Software engineers constantly cannibalize their own jobs, but there are so many positions for software engineers available (or potentially available) that we (software engineers) don't feel the affects.
There are some companies on a very predictable path. You could replace Eddie Lampert or Johnny Ive with a D20 mapped to management tactics and get pretty much the same outcomes at least on a short to mid term.
Plenty of competent companies have enough self-contained knowledge that you could make good decisions simply by surveying the on-the-ground employees, weighting them in some way, and generating policy that way. One would hope a widget factory with a combined 200,000 man-years of widget industry experience would know more about the widget business than a drop-in CEO that had to look up what a widget was on Wikipedia before he made his introduction speech.
I suspect the real justification for the wildly overpaid C-suite is that you need someone to be a scapegoat for Wall Street's whims.
A local and autonomous team that knows their market and is competent is not going to sack half of their own to finance a stock buyback, but a $30 million a year stuffed suit can impose it from above.
Most companies are like a train. The C level guys mostly report to the board where they think the train is going to be -- which is normally wag or ferry tail.
I know I am speaking in broad terms. There are companies out there where the CEO matters, but those are few and far .