The Urban Institute has released a study finding that states will spend $90 billion from 2014 less under the national health care reform law than they would without it.  The authors attribute those savings to reduced uninsured populations and greater federal financing of services that states previously paid for. 

From the report:

This report finds that state governments are likely to spend $92-129 billion less from 2014 to 2019 with implementation of the Affordable Care Act, thanks to provisions reducing the uninsured population and increasing federal support for health care previously financed by states. The authors find that, overall, the federal government would spend $704 to $743 billion more under reform from 2014 to 2019. Even after 2019, when the federal government's share of Medicaid costs declines to its permanent level, states will still come out ahead, realizing net savings in 2020 alone of $12 to $19 billion.

Full report: State Governments Would Spend at Least $90 Billion Less With the ACA than Without It from 2014 to 2019 (PDF | 459.33 KB)

Urban Institute.  (2011).  State governments would spend at least $90 billion less with the ACA than without it from 2014 to 2019.  Buettgenns, M., Dorn, S. and Carroll, C.