Lemmy.world federates with Threads and becomes the new reddit. Most people stay on it anyway since it has all communities and it’s still better than reddit used to be.
Ads are introduced since big instances now needs to be funded due to their size. The ads will be federated and there will be discussions about how everyone must support this model because instance admins need to pay their bills.
An alternative to Lemmy comes along without ads. It’s smaller but works in a similar way. People who cant stand ads move there instead. Eventually it gets the same problems as Lemmy has.
There will be a lot of fragmentation in the Lemmyverse. Users can’t stand seeing opinions they don’t support, so they will move to instances with lots of blocking and rules that support their own views. Inside this bubble they will enjoy seeing only supporting opinions and feel good while using Lemmy.