"varying" is a pretty wide range here. If you mean "trust" as in trust to maintain connectivity, yes, but beyond that there are established ways to create secure channels over untrusted networks. Could you provide specifics about what you mean if anything beyond basic connectivity?

>Anything over the internet needs to pass through routers and poof decentralization's gone

That's not true. Yes the strict p2p connection is gone but decentralization is what the name says, a network of connections without a single center. The internet and it's routing systems are decentralized. Of course every decentralized system can also be stressed to a point of failure and not every node is automatically trustworthy.