For a number of years now, the dominant technology platforms such as Google and Amazon have been flirting with how they might be able to disrupt the health-care industry, a critical and growing economic driver badly in need of new ideas and more data-driven approaches. Now the landscape seems to be shifting somewhat: Tech companies' interest in health care seems to be extending in other directions, and more traditional large "platform" companies such as Walmart are getting into the game while embracing data and technology internally. What's driving these shifts, and what might be the impacts on our health?