Depends, if they allow WhatsApp and Facebook to intercommunicate through it, then they could get 100M people using it by next week.
I'm not quite sure why I need two apps on my phone for communications through one company when 12 years ago I had one app on my desktop for 5 or 6 different company's messaging services.
off topic, but I absolutely hate the millennial put-down of 'ok boomer'. They use it for anyone who is older than them, regardless. I'm Gen-Z and being called a 'boomer' is offensive.