I don't think it's possible to take down decentralized social media unless it fails by itself, unless the ecosystem here is so completely unappealing people decide to get back to all the well known ills and dullness of Facebook.
Even compared to XMPP, it's not the same. Chat programs are a communication tool. Social platforms are communities.
I am not underestimating them, I don't know why this insistence that I must be. I think people are catastrophizing and spelling doom forgetting that we are seeing tech companies fucking up time after another, and also not giving enough credit to the advantages and potential that we have here.
If you think all it takes is peeking over the fence and the Fediverse will fall apart, the maybe it could never be. But I think the interest in something different will only grow now. I believe we can take users out of Meta instead.