The foothold it has over here in Europe (The Netherlands) is enormous. Everybody uses it, there's even neighbourhood watches that use it, see: https://cdn.nieuws.nl/media/sites/305/2015/12/05153708/atten...
Any advice? Just pull the plug and pay the social cost?
Turns out that people don't bother communicating with you if you're on SMS, and can never be bothered to write an email.
This implies that the communication they were going to send is not important. If it were, they'd write an email. And people don't like the cost of MMS and soon stop sending me stupid pictures.
I can archive email + SMS, not any of the other chat systems.
I hardly get bothered by any notifications or interruptions or silly photos unlike my wife's phone that is constantly binging and buzzing and silly comments from "family chats" and work chats eg. "lol rofl haha random internet picture"
It's refreshingly quiet.
If others can't be bothered to find a method to communicate with you, they can't be very sociable? Their friendship and social interaction with you seems to be tied to an app. That's not a social cost - that's a social price.
Some didn't migrate, but they are still able to reach me via email. I'm OK with that outcome of having lost some of those who didn't care.
It has advantages too - I get many of my friends to use Signal and I can avoid participating in many group chats that usually have a poor signal to noise ratio. Instead I just get a filtered report about the conclusion from one of the members.