The problem we faced is hiring people. We found that in order to attract talent, we had to let them use the shiny new technology. Otherwise it would be hard to attract anyone.
I think the real punchline there is just "hiring is hard", because elsewhere in the comments someone has made the argument that you shouldn't use shiny technology because it's too hard to find people (specifically, you'd be screwed if that one person left). Maybe that's a company maturity thing: fancy tech is good for attracting talent early, boring tech is good for attracting a sufficiently large ops team later.
Yes, this is the one addendum to the presentation. An organization must periodically refresh itself in order to continue to attract talent. As an organization ages, it acquires more and more code to the point that rewriting becomes unfeasible except on epochal timescales. Thus some natural expansion becomes inevitable. The key is to contain this expansion.
The problem we faced is hiring people. We found that in order to attract talent, we had to let them use the shiny new technology. Otherwise it would be hard to attract anyone.