While the outcome is still in doubt, the origin, and problem, with the plan is clear:
The essence of Obamacare, as of Romneycare, is a three-legged stool of regulation and subsidies: community rating requiring insurers to make the same policies available to everyone regardless of health status; an individual mandate, requiring everyone to purchase insurance, so that healthy people don’t opt out; and subsidies to keep insurance affordable for those with lower incomes. The original Heritage plan from 1989 had all these features. These days, Heritage strives mightily to deny the obvious; it picks at essentially minor differences between what it used to advocate and the plan Democrats actually passed, and tries to make them seem like a big deal. But this is disinformation. The essential features of the ACA — above all, the mandate — are ideas Republicans used to support.
http://krugman.blogs.nytimes.com/2011/07/27/conservative-origins-of-obamacare/?_r=0
Permitting private insurers to continue to monopolize the non-Medicare/Medicaid market, without a public option, is the the ACA's fatal flaw.