I think we're already there, functionally, but rather than a single great wall it is a cartel of smaller, privately controlled barriers directed to appeal to a collection of capital formations with similar interests. most people use the same big services running the same or similar algorithms to find each other, to communicate, and understand the world or anesthetize themselves through entertainment products. all of this is inundated with advertising and mediated by marketing campaigns to instruct us what exists and obscure / induce a forgetting of what does not exist for the casual user.
just as the libraries and archives have always existed for the truly curious party, so too will repositories and communities on the fringes of the internet. but they will be invisible and unknown to the average scroller scrolling on the app and giving a heart on the things that induce them to feel what they like.
why hide or block something when you can put highly profitable all you can eat burger and goon caves everywhere to obscure it beyond the power of memory to recall its existence?