Hi! The answer probably depends on what exactly you mean by ‘truly decentralized’. Different people mean different things when they talk about decentralization.
Going by the definition used on Wikipedia here, the Storj network and protocol are already entirely decentralized. There is no single centralized authority making decisions for all peers, and all peers make local autonomous decisions toward their individual goals. Storj is decentralized in the same way as Bittorrent: yes, there are points of coordination shared by multiple peers (in Bittorrent, these are the trackers), but anyone can set up their own point of coordination and join the network.
You are presumably using a more restrictive definition of decentralization, but it’s not clear which one, so you might need to be more specific on that point. You mention an orchestrated DDoS, so perhaps you want a system with no single points of failure? But existing satellites might satisfy that as well. Satellites are not single servers. A satellite is really just a trust boundary—so in practice they are many coordinating servers accessed through redundant load balancing.
And yes, anyone can set up their own satellite. The software is open source, which would make it hard for us to stop other satellites from existing even if we wanted to! But it can be nontrivial to host any application in a robust, reliable, and available way, so it takes some effort and resources.