Social media platforms are under intense pressure to actively censor online speech. The pressure comes from advertisers, corporations, special interest groups, governments, politicians and others.
The demands for censorship extend from authoritarian governments to brand-name advertisers to special interest groups.
Much online speech is censored depending on content and location.

• Advertisers are threatening to stop buying ads unless censorship programs are in place: Unilever threatens to pull marketing spend from platforms failing to tackle fake news
• Many well known brand name advertisers pulled their ads from Youtube in late 2017 due to Google running ads along side content considered objectionable by some viewers.
• Youtube has taken to demonetizing videos that it and it alone has decided contain objectionable content; frequently this is political content.
• Twitter engages in “Tweet throttling” and has shut down accounts containing political speech – but not containing hate speech, sex or violent acts.
• Online discussion forums, such as newspapers, actively use “shadow banning” and other methods to restrict dissemination of speech that someone found objectionable, including speech containing factual data sourced to U.S. government web sites.
• Canadian and US law enforcement ask Google to ban ads for cryptocurrenices: Regulator calls on Google to ban ads for binary options, cryptocurrencies
• Source: AT&T CEO’s net neutrality plan calls for regulation of websites | Ars Technica
• Source: Facebook Says It Is Deleting Accounts at the Direction of the U.S. and Israeli Governments
• Source: Instagram submits to Russia censor’s demands – BBC News
• Source: Governments are stepping in to regulate social media, but there may be a better way
• George Soros has called for social media censorship.
• Time Magazine has called for social media censorship.
• Facebook and Instagram were banned from China, and Google left voluntarily. They are welcome back subject to government censorship of content: China Will Welcome Back Facebook and Google — With Conditions
• The United States government surveils the online speech of all immigrants to the United States including lawful, permanent residents and naturalized U.S. citizens of the U.S. upon re-entry to the U.S. Such individuals are now self censoring their online speech to avoid running afoul of U.S. government authorities using unknown criteria to evaluate their online speech. Think about that: legal U.S. citizens are now self censoring their speech.
• Fake news cheapens and dilutes the value of content on social media.
• The overwhelming use of social media for the purpose of political propaganda dilutes and cheapens the value of content on social media.
• In the U.S., a meme is emerging that foreigners should not be permitted to post opinions on U.S. elections – literally, a demand to regulate political speech.

As you can see, everyone in a powerful position to do so, is calling for social media to be actively censored or is already actively engaged in censorship programs.
In the future, the only speech permitted on social media will be cat videos.
Until PETA complains about that.
Social media, as we know it today, is over with.