[generalk]

  > My point is that deprecation is by its very nature going 
  > to hurt something that isn’t prepared for its demise.

TFA describes techniques for deprecating code paths that do their best to notify and prepare the folks working with that code.

You're describing the end of Life of Adobe Flash that hits at the end of 2020.

Deprecation is different from EOL (Flash has been deprecated for some time now), and deprecating/EOLing a creation tool/product line has little similarity with tooling to deprecate internal APIs gracefully.

Although I do think that you and TFA agree on how difficult it is to deprecate functionality that folks rely on, it seems like you're talking about two wildly different facets of that statement.