In an analysis that does not account for any health-care reform bill, the Department of Health and Human Services projected that health care expenditures would double from the 2009 level of $2.2 trillion (16.2% of 2009 GDP) to $4.4 trillion in 2018 (20.3% of projected 2018 GDP). This provides us a baseline from which to predict the cost-control effectiveness of health care reform.
I'm somewhat bullish on the potential of the pilot programs and the excise tax to lower med costs for a given level of health outcomes, although I'm not supremely confident in that. I also think there is a long tail of events or technologies that could unexpectedly increase med expenses (that would do so with or without health-care reform). Furthermore, the current bill will expand coverage for a substantial number of people, as a result of which total expenditures will definitely rise. All things together, here are my (very rough) intuitions:
EDIT: I had this up for a few minutes with different numbers, before I remembered that the individual mandate and subsidies would raise med expenses significantly.
3.6 trillion in 2018 (17.7% of GDP), so we don't even need to argue about adjusting for inflation to judge these. Thanks Obamacare!
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.