If the “overheating policy” succeeds in sustaining US growth, what happens next?

The “overheating policy” being conducted in the United States consists in keeping fiscal and monetary policies expansionary at a time when the economy is at full employment. It seems that this policy is succeeding in sustaining US growth, by driving up the participation rate and productivity gains. But once this overheating policy has borne its fruit, what happens next? Growth will not be able to accelerate, since the economy will be at full employment and will remain at the modest level of potential growth; If a negative shock were to cause activity to fall, no economic policy response would be possible .