Bad analogy. Flash was never the core technology of the web, and it was proprietary to one company, which made it much easier to kill when that one company lost interest. It will take a long time for C++ to fade away, because of all of the useful code written in it.

If people actually got to make their own choice on that I'd strongly guess that Flash wouldn't have ever gone away. Browsers declared HTML5 was going to replace Flash long before it was actually capable of doing so (and arguably still isn't).

But it only took ~4 "deciders" to kill Flash regardless of what anyone else wanted, which was Apple, Microsoft, Google, and Mozilla (and eventually Adobe decided it didn't care about Flash anymore either). Nobody so centrally "owns" C++ such that there could be a concerted deprecation effort that anyone would actually care to listen to & respect. Even if the C++ committee itself decided to kill C++, and got G++, MSVC, and Clang on board, which is extremely unlikely, would anyone even care that much or just keep using the last release of the compilers with support until the end of time? Kinda like they do for FORTRAN. And COBOL. And etc...

Right. And a lot of the content is on Myspace, which is pretty much baked in to how everybody lives now. If you tried to launch some sort of rival service, even if it was as good as Myspace why would anybody join it? Next thing somebody's going to talk about handheld computers again, as if you could convince ordinary people to carry a computer around with them. Not likely.

More Seriously: You shouldn't believe any of this nonsense about how we're permanently locked in to something that's less than a century old. There are plenty of people still alive today who were born in a world that not only didn't have C++ it didn't have programmable computers at all.

Flash was never that integral to the web... There was a bunch of web plugins, flash was one of many... C/C++ is a different level altogether.

And thanks to tools like Ruffle flash is still alive and well, despite the coordinated effort to kill it.

It only went away due to browser vendors taking away plugins, yet it is back thanks to WebAssembly.