What do you mean "dying"? Facebook and Instagram are absolutely the dominant social networks / apps in most of the world. Sure there are insane amounts of bots, trolls, scammers and manipulators, but that doesn't make a platform "dying" while billions of people still use it.
I've had my account for over a decade, so I'm not really up to date with the current process. There used to be a period when you couldn't just sign up (I think it was invite only?)
Don't call it sideloading. Did you watch the video?