I’m not a doctor, but I have a hard time believing we’re going to use human behavior, or mask away, a virus that is as transmissible as chickenpox. Increasing vaccination rates will certainly help, but you’ll never vaccinate 100% of the world population. How do you totally eradicate a virus worldwide that’s this transmissible?
Again, I fully admit I’m not a scientist or doctor. And you are technically correct that “we don’t know yet.” That logic could be applied to anything. But in reading the literature, it appears to be widely believed by the scientific community that COVID-19 will become endemic… modest spread in vulnerable communities at certain times, but much more manageable than the pandemic level we have gotten used to.