The real revolution is a paradigm shift form the actual development focused on big of IT interests toward a classic desktop centered development, the needed ground is there and battle tested, the rest is "just" to be done on scale. A simple example: we have emails, almost any human on the planet have one, at least between those who use computers in a way or another. Today for 99% mail == webmail, something offered by some third party. We have some desktop MUAs but they are stuck in the '90s at best. However we have for instance OfflineIMAP, notmuch, storage normally big enough, so all we need to have emails on our iron is a MUAs friendly enough for end users, based on notmuch/mu like nomuch-emacs, mu4e, neomutt with notmuch backend and so on, that offer IMAP sync built in so and end user have only to enter relevant credentials and wait for the initial download time. The rest follow naturally.
Similarly you buy an IoT sensor? Your homeserver speak MQTT, CoIoT etc all you need is connecting to the sensor via LAN or to the AP offered by the sensor and then configure your WLAN. You see the sensor pops up in HA or something similar, that's is. No need of a third party "cloud". And so on.
The homeserver is simply a machine on 24/7/365 like most home "router", witch are actually embedded appliance, we only need them more powerful and open to be used by the end user, not only by the ISP. This "center point" offer "sync/services" to all families devices, that's is. The "cloud" became a simple backup/mirror of the homeserver for redundancy, availability, backup.