Don't ever think like this because that's impossible to happen.
We have an admin(s) responsible for this and maybe admins making sure that the forum will long last. In fact, the server of this forum was hosted by https://www.simplemachines.org/ which is an open-source web application that provides Internet forum and message board services based on their website.

So now, how this forum become offline if it seems we are in the decentralized website?