CNET:

The percentage of US adults who use a smartwatch will cross the 10 percent milestone for the first time in 2019, predicts research firm eMarketer. About 28.7 million Americans 18 and older, or 11.1 percent of the adult US population, will use a smartwatch next year, eMarketer said.

And:

eMarketer cited new features in the Apple Watch Series 4, which incorporates new sensors that can detect falls, one of the major causes of death for the elderly. If there’s an accident, the watch can place an emergency call.

A new electrocardiogram feature on the Apple Watch allows wearers to have a heart-rate monitor on their wrist. It can be used to detect a serious heart condition called atrial fibrillation (AFib), a fast heart beat that can increase the risk of heart attack or stroke.

Seems to me, as much success as Apple already has, a bigger adoption wave is coming. Apple Watch is opening the door to more people entering the Apple ecosystem.