So I have two questions:
1. What's the lowest-friction replacement (for Android/iOS/desktop or web) with comparable features and good privacy?
2. How'd you get people to switch?
Friends seem to like 'rich chat' stuff like gifs and stickers and all that crap.
Voice/video chat would be a bonus too.
People.. are these your real life friends and coworkers or online only? If they are real life people, they should be happy to contact you in whichever way you are reachable. Not sure why you would have to have facebook messenger otherwise fear dropping out of the social sphere. Is this a self-fulfilling FOMO situation?
2. You tell them it has cooler stickers.
How do you convince people to use one of them though?
Then accept that you will never hear from some people again. And shrug.