Maybe what we mean when we say we want a 'decentralized internet' is implicitly, that we want the popular nodes of the Internet Graph to be decentralized. That would be nice.
But I think we could realize that right now, the Internet is comprised of a ton of competing protocols, and as long as there's a translation interface that enables cross-communication, the internet will remain decentralized. That's impressive resillience. Kudos to the designers.
It seems to me that what would actually bring the most benefit to the structure of the Internet would be long-range wireless communication. Basically, the ability to use HAM radio to bypass ISPs. That would bring about a sea change in how the Internet is structured.