The Web (the WWW, upon which all websites are build) is less than 40 years old… I know this may seems like an eternity to younger people but it’s younger than me and during that short period of time a lot of ‘popular’ websites have vanished already.

So, yeah, all websites will probably end up going away. Even more so those belonging to Google (like YT) who is known for not minding killing perfectly fine websites and services…