I think the house of cards is also potentially diamond shaped, where a lot of systems are built on top of other systems the organisations no longer understand,

I think the house of cards is also potentially diamond shaped, where a lot of systems are built on top of other systems the organisations no longer understand, which are held up by a single engineer that has been there long enough and holds enough IP to know where to look when trouble strikes. Basically, if a pulled card collapses a few levels you're maybe ok, but hit the widest part of the diamond and you better hope that engineer is around. Take the engineer away and you have a reeaally precarious, potentially very expensive house of cards. I have a hunch this is not uncommon, especially as the upper levels of cards fill with 'automation' and abstraction.