I’ve thought about it a bit and the Fediverse has been around for a while now. There are some really cool applications being made to replace the mainstream ones, but they just aren’t taking off.
Why do you guys think that might be? Ease of use? Addiction to the mainstream platforms? Lack of marketing?
That would require easier instance switching (like nomadic identities on Hubzilla). But also the very idea of a “main” instance is counter-productive. The current theme based instances is a better idea to cater to the current niche audiences.
Maybe in the future there could also be more mainstream regional instances. Something similar to your regional/city newspaper, where it is more about local content and localized exchange.