I'm afraid of the same outcome too. However I think many admins in the Fediverse are aware and I expected most servers to block any instance from Meta.
Having an instance with a x million users is impossible to moderate. Instances have been blocked for not being able to moderate low thousands of users due to incompetent/unresponsive mods. Having a poorly moderated instance federate with yours is seen as a threat to your users and a proactive admin would not allow federation. Also most admins are aware of EEE tactics and we all know we cannot expect anything even remotely resembling ethical behavior from big corporate instances, they are a threat to the network by default.
I was just going to reply with EEE, but the situation you're describing presents a problem.
Suppose the network wants to be able to handle billions of users, but you want to keep each instance "small," i.e. thousands of users.
Then you'll have millions of instances.
Having each instance manually curate a list of others it federates with isn't going to work, but neither is instances not federating with the large majority of other instances.
You all need to figure out a way to get rid of this instance-level whitelisting or blacklisting, because that ends with either Meta or an intractable scalability problem.
Humans demand connectedness. There's something to be said for participating in seven independent communities with seven independent accounts, but when you see something from Community A and want to share it with Community B, a system that doesn't allow either account to make that connection is going to frustrate people, and get outcompeted at the system level by something that does.
