Looking to the future, the report added, "the Medicare program is not sustainable in its present form."

I doubt such policies are sustainable in the long term.

Whether this model is sustainable in the 21st century, however, remains to be seen.

This approach makes sense, but it might not be sustainable in the long term.

It would not be sustainable or stable in the long term.

This growth rate was not sustainable in the long run without more reforms.

It is just as important that we make development sustainable in a long-term perspective.

This is of course not sustainable in the long term.

These four questions are fundamental, I believe, if economic growth really is to be sustainable in social and environmental terms.

That system is simply not sustainable in such an institution.