As we all know, driving west in New Jersey is unsustainable. After all, if you keep going west, you will eventually end up in the Pacific Ocean. That's pretty damn unsustainable. It would have been helpful if the Washington Post had clarified for readers that when the Republican health care experts cited in this piece called Medicaid "unsustainable" they meant it in the same way.
The Republicans were celebrating the prospect of the Senate's health care reform bill which includes large tax cuts for rich people, which are coupled with large cuts to Medicaid. The economists justified these cuts by proclaiming Medicaid to be unsustainable.
This is true in the sense that spending is growing faster than the economy. Of course the same would be true of any category of spending that grows faster than the economy, like federal payments for various types of social media and any other category that might be seeing rapid growth for a period of time. If we projected out a rapid rate of growth for the indefinite future, it will eventually cost more than the whole economy. It's just like driving into the Pacific Ocean.
As a practical matter there is no problem with covering the cost of Medicaid for moderate-income people, the elderly, and the disabled far into the future, if we don't give big tax cuts to Donald Trump and his rich friends. We can and should look to get the costs of the program down by bringing what we pay for drugs, medical equipment, and doctors in line with other wealthy countries. Of course, this is a route that Donald Trump and his rich friends probably do not want us to take, nor does the Washington Post.