WhatsApp is a real hard breakup in much of the world. It's the defacto standard for communication around here, and even a bunch of businesses use it exclusively. One can hope the EU will eventually mandate unlimited SMS on cellphone plans, but I don't see WhatsApp being dethroned another way
I doubt it.
Here in France, cell plans have had unlimited SMS for a very long time now. Yet, WhatsApp still is extremely widespread. Now, I'm not the most socially connected guy around, so I may not be attuned to any new developing trends in the matter, but IME it doesn't seem to lose any popularity, and something like 95% of the people I interact with on WhatsApp are locals.
None of their other apps come close. It doesn’t even look like a Meta product to me.
What I'd like to see is interoperability so that I am not forced to use Whatsapp because everyone else is using it and my friends in the US aren't forced to buy an iPhone just to use iMessage