It's already the major protocol in many countries. A decade ago people were laughing, saying IPv6 will never break 10% adoption. Now it's 50% and somehow people are still making the same joke. Are we insidiously shifting the goalpost somehow?

I don't know 'bout you but ots of services are confident enough in the technology to allow IPv6-only as an option, see eg. Hertzner.

At this point one has to be borderline delusional to think IPv6 is only viable in another 25 years.