What about Medicare? For years, many people — myself included — have warned that Medicare is a much bigger problem than Social Security, and the latest report from the program’s trustees still shows spending rising from 3.6 percent of G.D.P. now to 5.6 percent in 2035. But that’s a smaller rise than in previous projections. Why?

The answer is that the long-term upward trend in health care costs — a trend that has affected private insurance as well as Medicare — seems to have flattened out significantly over the past few years. Nobody is quite sure why, but there are indications that some of the cost-reducing measures contained in the Affordable Care Act, a k a Obamacare, are actually starting to “bend the curve,” just as they were supposed to. And because there are a number of cost-reducing measures in the law that have not yet kicked in, there’s every reason to believe that this favorable trend will continue.

Furthermore, there’s plenty of room for more savings, if only because recent research confirms that Americans pay far more for health procedures than citizens of other advanced countries pay; that the price premium can and should be brought down, and when it is, Medicare’s financial outlook will improve further…

But haven’t all the great and the good been telling us that Social Security and Medicare as we know them are unsustainable, that they must be totally revamped — and made much less generous? Why yes, they have; they’ve also been telling us that we must slash spending right away or we’ll face a Greek-style fiscal crisis. They were wrong about that, and they’re wrong about the longer run, too.