This was a goal of ActivityPub but it'll take a lot of work to get there. I'd love to see the fediverse evolve in the way you're talking about but I don't think it will while mastodon remains the dominant platform. The masto team did a partial EEE (they did the embrace/extend part) years before Thread was around and they've dominated the fediverse ever since and most people refer to this place as mastodon. The masto dev team has said multiple times they're not interested in adding support for other content and they want to remain a microblogging service.

Other service have to remain compatible with mastodon to gain any traction which makes getting a new project off the ground more difficult. Lemmy was around for a couple years before the reddit migration and you'll notice kbin is just about as big as lemmy despite the head start. Outside of some new huge event, the fediverse will probably continue on as it is for a while. I'm really hoping lemmy/kbin can gain a large enough userbase to throw some weight around and influence other projects development so we can see some evolution.