HealthCare.gov is going to see some shrinkage in 2016. The number of health insurance plans available on that huge federal Obamacare marketplace for 2016 is decreasing by up to 12 percent compared with this year, industry sources told CNBC. And there will be an even sharper reduction — of more than 40 percent — in the number of health plans on HealthCare.gov known as PPO plans, which offer customers the most flexibility in where they can get medical services covered by their insurer, sources said.