Especially older online only games will probably disappear forever.
Most offline games will probably always be available to some degree. Games for exotic hardware like old phones or weirdo consoles are likely going to the dustbin of history.
Maybe some future advanced AI or some schizo madman blessed by the heavens will develop emulators even for those tho.
87% Missing: the Disappearance of Classic Video Games | Video Game History Foundation (gamehistory.org)
New study reveals most classic video games are completely unavailable