I've been hearing a lot about much heavier blocking and opt in federation. If I were to predict how it all ends up, I see 10-100k users on a small group of servers siloing themselves, and the rest of the fediverse remaining as is. Or even opening up more than it is currently as the loudest people calling for it silo themselves away from the rest of the fediverse.
I won't say that one particular model is against anything or wrong, the point of free software is the freedom to use it in the manor preferred and if people get value from a walled garden then more power to them. Just not for me.