Re: Three things
"Replacing Bob (30 YE) with 3 months notice is a bad thing because he can't ensure that everything that needs to be transferred has been transferred."
Yes, 30 years experience of CA-7 is a good thing, but a system that relies on 30 years experience of *that particular* CA-7 environment is a very bad thing as it implies there is zero documentation or processes around it. And to be clear, I'm talking about more than commented code, I'm talking about design docs of various levels.
The problem is that there is no Joe, Simon and Fred willing to move into these roles and stay there for 30 years. The long-term model doesn't work, there is no job for life any more.