I think there would have been a general increase of users from 2019, due to highly publicized happenings. These users would be more political in nature, and more prone to exhibit new habits, whether high quality or not. Think of more Qboomers, more young people who heard about 8chan from halfchan or social media. More crossposts/reposts from Twitter or 4chan. And I'm sure older folks would start to stay within their niche boards and communities. Perhaps a lot of boards may have developed a stronger "elitist gatekeeping culture" (by way of memes and catchphrases) to defend against these new types of zoomers and Qboomers and their posting habits.
That's another thing. 8chan 2024 may have had hundreds of small but flourishing communities. There would be a niche and rich cultures that would cater to anyone.
I could see another scenario where the site starts bleeding higher quality and older folks due to incessant meta happenings.
Things like complaining about the quality of X board much, then creating a new board that splits users.
Such things happened countless of times with /intl/, /animu/, /b2/, etc, but perhaps it may have happened a bit more past 2019.
And another timeline where Jim starts to favour QAnon over gaymergate, thereby shifting the tide of the entire site. Implementing more rulecuckery to uphold non-boomer frenly content. Freezing board creation. Destroying infrastructure, etc. It may lead to a similar result as our current timeline.
Overall, I would like a site like 8chan to come back. For a time in 2020, infinityNext seemed really promising, but multiple factors drove everyone away. And the site was killed.
Of course, the users would be different, given that they are new, the old 8chan ones aren't coming back.
Though, I'm not entirely sure how to get a mass-exodus of people from halfchan, like gamergate did. Or like how null got his kiwifarms / iFunny base over to 9chan.tw for a while.
We'll see how this plays out, but it's really regrettable that 8chan lost.