I think it's important to separate Bluesky the company from atproto & "the atmosphere", i.e the collection of apps, feeds, labellers, relays, jetstreams, and other participants in the network.

The atmosphere and the PDS are definitely trending towards a single database for all your things. All of the examples you cited are being worked on in one form or another. I'm personally working towards a Permissioned PDS which can power Google Workspace like experience on ATProto, where there is an existing understanding of how sharing, visibility, roles, and permissions work across groups of people (IAM). Permissioned data unlocks an entire (majority) of applications people want to use, but won't until they can do it without broadcasting everything. There are a number of ways this may play out, several will materialize as options, i.e. some apps need e2ee and others cannot have it for the experience they want to deliver.

The overarching ethos is user or individual choice, paired with credible exit, enables real competition. Let's go wild, build all new apps, and let the people decide what they prefer. More indie, less winner take all