To build on your metaphor though, there are cabbies with "the knowledge" in London, and probably similar folks in Paris. The way I have seen this work in tech i

To build on your metaphor though, there are cabbies with "the knowledge" in London, and probably similar folks in Paris. The way I have seen this work in tech is, you have to keep the people who know where the bodies are buried around for a long time, and others will use them as a resource to inform their efforts. The alternative, of letting them walk over the years, is that large sections of your stack will have "here be dragons" written over them and become no-go zones where your only option is to route not only engineering but business efforts around them.