Is Decentralized Really Possible in a Useful Structure

Face it, the moment that an exchange starts to get involved in a crypto's life-cycle the decentralized part fades some. If the exchange was simply a website that showed data directly off the blockchain and somehow tagged the other coins wallet in the meta data or something, then there was still a chance, but to do the job safely and right, you are going to need a database and structured security and that is where the decentralized part goes away. You have simply taken the power that you gave the banks and ACH's and given it to the exchanges.

They will not provide the private keys and they can stop and start the wallets, TX's and staking anytime.

Tokens, instead of coins are often fully in the control of the dev's or whoever is behind the token, and that makes a dangerous place. There is really nothing that can get us back to the wallet to wallet world, but we have to watch just how much control over just how much money we give these sites and people.