Re: What about our networks?
You are correct, but I can't see that changing any time - at all, not just soon.
ISPs don't care - as long as the router they ship to you "free" is a) cheap to them, and b) allows you to reach WhatsTwitFaceBorge then they are OK.
As to segregated networks, there are some real practical problems there. As it happens, SWMBO just got an Echo Dot - no I didn't buy it, I don't want it in the house, but SWMBO says otherwise and one of our daughters got it for her birthday present. I setup another SSID to connect it to with client segregation turned on - but then I also need to put SWMBO's phone onto a specific IP address and configure the network to allow the phone and the Dot to talk to each other. I'd use VLANs as well but none of my switches are VLAN capable and I'm not keen to spend on that right now - but if I did then that would complicate things even more as there'd be no ability for the config program to find the devices it needs to configure (usually based on being in the same broadcast domain). Of course, VLANs on a wired network would mean that you can't just randomly plug any cable into any socket where it fits - yes, that's the level of many people, if the plug fits then it must be the right connection (even if it's an RJ11 phone connector into an RJ45 network socket).
Now, I can do this as I've been in the IT business for <cough> decades. Your average user will not be able to even grasp the concepts. And automation really really will not cope with it.