I don't think that FAQ entry answers the question asked by the parent comment.

They say that they don't want to decentralize the service (as in, everyone can run their own instance), and I can understand their stand on that. However, they say nothing about federation with other similar attempts that are popping up.

Instead of "Will I be able to run my own instance?", think: Will I be able to follow an Openbook account from my Mastodon account?