That's a good question, and probably too early to know for sure given all the shifts and changes currently happening. I'd say the platform could go either way, and probably will oscillate between the centralised/decentralised extremes over time.
On the one hand, the idea of it is obviously focused on decentralising and letting everyone have their own instances; on the other hand, people tend to cluster, we like to see and be seen, there's a thrill of pride in having people acknowledge and react to your words and a converse feeling of emptiness when you make a brilliant observation and no one is there to notice it. It's that desire to be part of a larger group that will inevitably lead to some centralised nodes in the fediverse and a bunch of ghost-instances floating around with one or two dedicated/lost individuals posting into the void. Within those busy nodes is where the same cycle of push-pull between "everyone gets a say no matter how unhinged" vs. "I'm in charge here so I decide who gets to speak" will play out.