This article presents projections of Medicaid spending and state and federal revenues through 2045.  The authors conclude Medicaid spending will average 16.6 percent of national health spending from 2006 to 2025 and then increase to 19 percent of national health spending by 2045.   

Kronick, R., & Rousseau, D. (2007). Is Medicaid sustainable? Spending projections for the program's second forty years. Health Affairs, 26(2): w271-87. 23 Feb. 2007. DOI: 10.1377/hlthaff.26.2.w271. http://content.healthaffairs.org/cgi/content/abstract/26/2/w271 © 2007 by Project HOPE.