Here's a question ... Once Flash is gone, what will happen to the many games on facebook that require flash? Will something be developed to take the place of Flash and permit these games to work or will the games just be gone for good?
It's up to the content developer to migrate to a different technology or not. It's entirely up to them. Adobe announced Flash Player's end-of-life over 3 years ago, in July 2017, giving content providers sufficient time to migrate their projects.
And to be clear, if the game developer doesn't do anything, yes, the games will just stop working for almost everyone. (A few techie people will be able to keep old computers running, though it's risky).