The U.S. Senate passed the health-care overhaul this morning, which means there's probably only one very risky step left before some sort of reform becomes law: reconciliation of the House and Senate bills.

Assuming the bill doesn't go off the rails at that stage, here are two things to keep worrying about going forward, one medium-term and one long.

Medium-term, as a number of people at Talking Points Memo have noted, there is the fact that big changes in the bill aren't supposed to take effect for years -- 2013 in the House version and 2014 in the Senate. That leaves years for citizens to feel that the big reform changed nothing, and it leaves the new law vulnerable to reversal if the Democrats lose their majorities in 2010 or 2012.

Long-term, the fundamental problem with health-care systems over time is that they take up a larger and larger share of national income, reducing the amount of money people can spend and invest in other things. This is true all over the world, regardless of insurance systems, which is why health-care is a political problem in Europe and Asia as well as in North America. As Atul Gawande recently pointed out, medical care in the 21st century is on its way to taking the role agriculture had in the 19th: The economic undertow pulling against economic advancement.

In today's rich nations, the agricultural drag was removed by hugely increasing the productivity of farms (certainly one reason those nations became rich). Can medical care likewise be made more efficient? Certain steps seem obvious: Pay doctors and hospitals for per patient, rather than per procedure, so they don't have an incentive to do more than is necessary. Cut back on expensive high-technology gizmos whose overuse can cause disease as well as cure it. Make the system more rewarding for physicians who focus on primary care, prevention and geriatrics than for expensive specialists. Maybe the new law's pilot programs and experiments will suss out the best means to make those kinds of changes.

In the longest run, though, it does seem that over time, people with good health care want more of it, not less. (It's amazing to think that the architects of Britain's National Health Service predicted that costs would stay steady because demand for medical care would fall as people became more healthy; instead, of course, the definition of "good health'' changed to include more care, and costs kept rising.)

In that long run, then, it may be that societies all over the world will have to decide which is the lesser of two evils: "Too little'' care or "too much'' cost. So far politicians everywhere perpetuate the fantasy that people can have the opposite--more care for less cost--but that myth won't last forever.

It's great the American medical system looks set to become more accessible, fair, and flexible. But the big issue isn't going away any time soon.