Google is already killing itself. The search experience has been getting steadily worse and worse on one end, but on the other, they're slowly strangling the incentives that were offered to publishers (ranking, traffic & monetization) to develop content for the "open web as dominated by Google".
Now, everyone who's running a website for a living is doing platform-native content for traffic and pairing it up with a newsletter-backed website or straight up investing in brand advertising campaigns to have access to their own audiences still, without relying on Google to deliver them.
My guess is that we're in for the second wave of Big Aggregators, but it's tough to say what the technological twist behind it will be, so it's not just a reddit 2.0.
Not an OP, but I think the search monopoly is likely to end within the next 10 years. There were fundamental reasons that kept it alive and all of them are becoming irrelevant at various speeds.
Not that it must kill Google, they can still pivot and e.g. Google Cloud is already non-negligible in their revenue structure. But I'm relatively confident that search/ads duo won't be their main earner anymore just like Windows is not the main earner of Microsoft.
So when is it gonna kill Google?