TINT I don't believe, that there will ever be an actual free speech platform. This is because every platform is run by people and everyone has their personal interests which they will try to protect.
There is only one way it can happen, if someone hosted a forum or such other on the darkweb and just let there be no moderation. It wouldn't last long, but it would work for a period of time. It could possibly work long term if absolutely no pictures could be posted, as it would be harder to take down a forum that only has text.
