Look man, Flash was not the same thing and people need to stop bringing this up.
Flash was a third party plugin that got way out of hand. It wasn’t (necessarily) the job the browser vendors created for themselves and offered for years.
Flash was also moreso removed on a fledgling platform first that grew to be a dominant platform; it wasn’t killed off on an existing dominant platform first.
You've completely disregarded the other examples of breaking changes that have already been made. The open web still survives afterwards. The web isn't immutable no matter how much people might want it to be.
I called out Flash. I could not have written a more straightforward note about how their comment was set up. Nothing I said indicated I disagree with their overall stance, just that Flash is a ridiculous thing to trot out.