In this video I discuss how 4chan.org was hacked by using old insecure php code in the backend of the sites software (yotsuba) which lead to the administrators being doxxed and having to take the s...
If they don't fix the vulnerabilities their site had then putting it back online would just lead to continuous hacks. I'm guessing it's going to be a massive overhall. 4chan was started by a 16 year old in 2003 and really hasn't changed much since then.
It's not easy to upgrade from php5.5 to modern day to say the least. It will take a huge effort definitely since the code was all maintained by the old owner, at least that's what I got out of the video.