Those business are ad aggregation companies by default for the most part, and they aren't gonna to survive without clickthroughs
Yes, this is it exactly. The web pages that depend on ad revenue are the ones in trouble here. They're being undercut by pages that give people the information they want without going through all that stuff.
You're confidently predicting that the AI summarizers are going to fail somehow, and then everything will just magically go back to the way they were. I suppose that's a reassuring thing to believe. Why should I believe it, though? The AI genie is out of the bottle. I can run one locally on my computer if I want. All the existing online summarizers could go bankrupt tomorrow and I'll still be able to get an AI to distill the information I want from the morass of ads and engagement-harvesting click farms.