(Undated) -- In many of the state-based insurance exchanges, Medicaid enrollment is running well ahead of sign-ups for private insurance. That's what a CBS News analysis shows today. There's concern that if the trend continues, the system known as Obamacare won't work because there won't be enough healthy people buying private health insurance. In Kentucky and Washington state, more than 80-percent of people who've signed up for insurance since October 1st have enrolled in Medicaid. In New York, 64-percent of new enrollees opted for Medicaid.