I’m certain that some activitypub implementations will be normal with some normies (governments/ universities creating their own socials), but also certain there wasn’t be one implementation that all normies are using.
In the same vein I think there will be a greater portion of users who are active on many platforms. 5 years ago most people engaged with content on a single chosen platform. In 5 years most people with engage with many platforms.
I think the common theme amongst all platforms will be a desire to control the content we see.