I woke up to a lot of drama in the fediverse concerning the future of ActivityPub and how it compares to AT Protocol. Reading what others had to say, some of it got a bit heated.
I think the biggest problem that ActivityPub faces is that the more popular platforms are not interested in implementing new features. So you have this situation where smaller platforms are trying to innovate in ActivityPub, but the larger platforms won't recognize any of those innovations.
For example, Mitra and a new project called Forte are collaborating on nomadic identity over ActivityPub. Once it is stable, it will probably be ported over to Hubzilla. Out of hundreds of projects, only three would support nomadic identity.