What we could do is increase the number of IP addresses available. Just imagine if we enlarged the IP address space from 32 bits to 128 bits: Every device on the Internet could have a unique IP address!
Why do all those devices need to talk to each other btw? It's never specified. Is it a user need or a data collection/spyware need?
In a world where security articles make the news saying that you could obtain access to something IF the attacker already has local root and IF the moon is in a quarter phase and IF the attacker is physically present in the same room as the machine and this means the sky is falling...
... we should be questioning why disparate devices on unrelated home networks need to talk to each other.
For security there is still the firewall
The whole idea of the internet from the beginning is that devices can talk with each other.