The thing that will be the death knell for Google search will, ironically, be something they've done to other technologies. Commoditized absorption. In 5 years nobody (or EXTREMELY FEW people) will go to a page to use a search engine. Search is being absorbed into the interfaces people use to get to the internet. This started when the default behavior of the address bar in a browser stopped being "cannot reach that address" and became "you typed in something I can't get to, let me show you a search engine search for whatever that was you just typed in". Google could survive with this since there was legal precedent to force MS to allow Google to set itself to be the default that Edge/IE used, and they had their own browser (Chrome) where they would be the default.
But it isn't stopping there. It's absorbing deeper into the connected lifestyle experience. AI driven contextual enrichment searching is now being baked into apps (Grok in Twitter for instance), things like MS Copilot are baked into the OS, Apple head also doing this. The "assistants" on both Apple and Android phones are now just extensions of the manufacturers AI which handles the searching for you. Google is being pushed further and further to the back, even on it's own phone OS. It's last line of defense is becoming that their own AI is deeply integrated with Android (i.e. it's what answers when you "Hey Google" your phone now). But all we have to have now is Elon to sue Google using the same "You can't block us out of being an option for search just because you own the browser" argument they used against MS, but substitute browser with Phone OS. It will happen, there are those already working on the Android OS open source side to do it for the industrious tinkerer....
Unless Google discovers and pioneers a "Next new thing" they're now an "old stock" heading towards inevitable decline, IMHO.