Based off your post here, I question how closely you follow Apple. The reason I say that, is we already know there are ‘sleep tracking apps‘ available long before Apple releases their rendition, but you’re questioning how Apple could promote something that they will create natively? (That probably has years of work in involved) They’ve been doing this for years for tons of features throughout the iPhone, iPad and they sell those points to consumers to upgrade based on Technology from other competitors. And you’re under the notion that Apple ‘can’t promote‘ something that they may put a unique emphasis with sleep tracking?
There was an article I believe two years ago, where Apple was working with ‘sleep specialist‘ on studies, patterns and overall Tendencies for sleeping behavior, and I can guarantee you, they will probably have a much deeper aspect on Sleep tracking, And I guarantee they will find a unique way of promoting this with how well they market their devices