All it would take is WhatsApp going paid plans only. All of Europe will switch to Telegram as primary messaging platform in a couple of days. Hence a paid only WhatsApp will never happen until every plausible alternative will be made impossible either by acquisition or by law.
Whatsapp became successful by being cheaper than SMSes in Europe. But yeah people probably switch to the next convenient app.
> All of Europe will switch to Telegram as primary messaging platform in a couple of days.
I don't think you realize how much Telegram is associated with hated Russia and the local far-right in several European countries.