This is very similar to what happens in many Latin American Countries, but they use WhatsApp instead of Line.

The phone companies got greedy and priced the individual SMS so high ($0.06 local) that nobody uses them except for 2FA codes and notifications.

If sms where still $0.02 each as they were in the early 2000s I would still use them occasionally.

iPhone users here (10%) are not really aware of iMessage because they use WhatsApp.