Wow you sure are optimistic
The reason people seek out the fringe nutjobs on the internet is because research shows people don't like having their beliefs challenged. So more mainstream news sources (and even Fox News fits in there as they don't have an unlimited ability to lie to people, as the Dominion suit proved) have suffered as people search the internet until they find someone who will confirm what they believe, or want to believe, and take them ever further down the rabbit holes.
With AI they no longer need real people to spread the lies. Real people are a problem, because like Alex Jones or Rudy Guliani can be and have been held accountable for their lies in a court of law. There is no one to sue with an "AI personality", especially if the operator is overseas like say in Russia. It also doesn't have to say the same thing to each person, it could tailor what it says to hit the hot buttons with each person. So for one person it might be spreading more election conspiracy lies, for another it is going on about democrats and Hollywood elite drinking the blood of children, and so on. Some people who it judges as more likely to be willing to commit violence can be groomed to become a private militia to do the bidding of whoever is behind it.
The people who listen to fringe figures like Alex Jones, or maybe those further fringe I've (thankfully) never heard of, aren't going to go back to watching Fox News because AI will make them "not believe anything they see on the internet". They will have a customized Alex Jones type but far worse, who knows exactly what to say to push that person's buttons and watches their reactions to know what to back off from (maybe they have a soft spot for gays because they have a gay brother, or for immigrants because their uncle was an illegal) and what to go all in on.
There's no way AI is going to bring back mainstream news sources for those already lost to the fringe. But it will eventually kill off the fringe figures making videos on Youtube or Twatter today, so I guess there will be some good accompanying the massive downsides.