So PewDiePie will be deleting his channel "soon", and there's actually a legitimate reason for it. He currently is sitting at 49,822,834 subscribers, and will be deleting his channel once he crosses the 50,000,000 subscriber mark.
For a short example, two videos both have 2 million views, the first has 200,000 subs, and the other, PewDiePie's, has 50 million. Both make the same amount of revenue per view, but only the first will be displayed on the front page of trending videos.
The reason is Google's current algorithm for displaying videos on the front page. YouTube is promoting channels based on percentage of "audience engagement" (subs to comments & likes ratio), which means his videos are getting turned down by the algorithm and not showing up on user's feeds.
So, by having 50 million subscribers, and the fact that only 4% of his subscribers watch his videos now, it is actually killing his channel slowly. As time goes on, the analytics show that he is getting less revenue the more he works and puts out videos, and because he almost has a zero percent chance of being shown on the front page anymore, he has far less of a chance of bringing in new, active subscribers. So in the end, he'll make less money by having 50 million subscribers.
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I think it's a brave move, regardless what you think about him. I know almost no one here likes his channel, but still, deleting 6 years of your life's work in hopes to starting something new, and hopefully better for you in the end, is a bold and risky move.
He's a smart guy, and taking a risk, but it's probably not a risk at all. He'll have a brand new channel, with a huge spike in subscribers following his movement, which will land his videos on the front page. That will attract everyone who is "where did his channel go?" and resubscribe, while also bringing in new people who aren't subscribed or some how don't know who he is, who were just browsing the front page.