I work in a family engineering business.
30 years ago our top cnc machinist announced he was leaving.
Oh no, what will we do without Dereck, he's sort of irreplaceable.
Now up steps my brother with a degree in Mechanical engineering, (who was pretty good on the lathes side of things)
he went and did some serious reading about milling and cnc milling
The upshot, we realised that no one is irreplaceable and actuallly Dereck wasn't that good.
So, from a playing perspective, there is always someone that could do it and do it well
if you're the BL then that's a whole new game