IMO it's almost certainly not the "open letter"; Flash was Adobe's effort of having a runtime that they controlled, to enable authoring rich content - you need

IMO it's almost certainly not the "open letter"; Flash was Adobe's effort of having a runtime that they controlled, to enable authoring rich content - you need to understand that Adobe didn't directly make money from the player, and the publicity it got from it was increasingly negative due to the usage in ads (which were often not very carefully programmed, if I may add so). So you have this combination where Flash Player was costing Adobe lots of money to maintain, while not contributing too much to the topline; and on top of it, we made a prototype of CSS regions (basically reflowing text inside/outside arbitrary shapes) that was met with a lot of initial enthusiasm by all browser vendors/ they all seemed eager to adopt it. So the executive that was in charge of the digital media division just saw the opportunity to cut huge costs, and put Flash on life support basically overnight - by basically outsourcing the runtime work to the browser community, and contributing as Adobe in the points where we felt it was essential. There's stuff that I'm not sure I can tell even now even though it's old news... but let's just say that there were very big industry players that were taken by surprise and would've otherwise supported Flash; the death of Flash on mobile and on the web at that point was far from being a foregone conclusion (in fact, Flash support was being touted at the time by Samsung as one of the reasons why Android is better than iOS). Now - don't get me wrong, I was not in any way among the decision makers. But I was in the development team - both for Flash player and for the prototype that I believe sealed Flash's fate. I may be wrong; but OTOH there's a good chance my recollection of the events is far closer to the truth than the random internet narrative.