As per a January 2012 study, if the PPACA is enacted, it would reduce the number of nonelderly uninsured Americans from 50 million to 26 million. If however, the Individual Mandate clause of the PPACA is repealed, the number of uninsured Americans will rise between 40 and 42 million.*
The complete report can be found
here
* This study simulates the main coverage provisions of the ACA as if they were fully implemented in 2011, and compares results to the HIPSM baseline results for 2011 without implementation of these reforms. This approach differs from that of the Congressional Budget Office or the CMS actuaries, who by necessity provide 10-year estimates.