@mlabowicz People keep saying this whenever there's mention of a major implementation of activitypub, but I really fail to see what the extinguish part is supposed to look like.

People on the rest of the fediverse won't go anywhere if this takes off - if anything, they'll have increased incentives to stay where they are as there are more people to follow. If this service became popular and then dropped support, at worst it would just leave the fediverse exactly as it was.