EEE would require existing Mastodon users moving to threads
It would not.
Meta could implement ActivityPub in Facebook, and there’s your majority population. Imagine a Facebook user “friending” your mastodon account. You follow them back because it’s your mom, and so does basically everyone. Next, Facebook implements Pages to round off the concept of “communities.” Then, Facebook introduces a genuinely useful extension - marketplace. Once a decent clip of people set up shop, trim off any instances that don’t adopt the FriendlyPub fork.
Bam, EEE.
Memory Alpha has a pretty good article explaining the Library Computer Access and Retrieval System (LCARS).