There has been much controversy in recent times over censorship of search engines and social media. According to those engaging in this, it's done with good intentions. Whether this is true or not is missing the point. Why are we relying on a centralized search engine at all that can censor, when we've had decentralized search for a half-century?
DNS can be seen as little more than an indexing service. There is no fundamental technical reason why the exact same approach can't be taken for resources at particular domains. Every site could publish their sitemaps and tags quite easily, and many do right now. They simply upload them to search engines rather than having them be well-known records considered by peers.
A DNS model would in fact simplify search indexing a good deal, as you can drop the crawling code entirely and simply wait until at least one person accesses a resource to index it. This would put the burden of crawling/advertising their available pages on site operators themselves, pushing costs down the stack, as is appropriate in a decentralized system.
Much of the reason DNS is tolerated as a decentralized system rather than centralized is that it takes so little resources relative to the rest of the web stack. People love the idea of federation, but hate paying for it. The primary question is whether incentives align for the current parties running DNS to also index and cache content hierarchies.
The answer is obviously no, or they would be doing this right now. This is once again due to the primary browser vendor (google) having no interest in supporting such a thing, as it would actively undercut their business model. If a browser did support such a system, many content creators and web hosters would absolutely love to adopt a system with clear rules under their control rather than the morass of inconsistency that is the centralized engine's rulesets. Similarly, the ISPs and Web Hosts would happily hop on board to the idea of offering yet another service they can charge for.
Therefore the question is can the existing business model of advertising that subtly corrupts search results translate to a decentralized system? Of course it can. The trouble is that it'd be the ISPs and web hosts in the position to extract this profit. This is in fact the ray of hope in this situation, as both Google and it's competitors in the (virtualized) hosting biz could get a large piece of this pie.
So, if you wanted to know what a future with this would look like it'd be that Microsoft or Amazon forks Chrome. This has already happened in Microsoft Edge. From here it's but a matter of modifying and open-sourcing their existing indexer, and making their fork support it's use. Introducing a system of decentralized search would both hurt their competitor, and be another reason to use Azure versus GCP and Amazon. They'd likely adapt Bing to leverage this as well, to extend the benefit to all browsers.
That said, Amazon or any large host could execute on this. Much of the tech that Cloudflare uses to cache content could likely be re-purposed towards these ends as well. There's a lot of money to be made in disrupting the status quo. Whether this translates into concrete action is anyone's guess.