What is a "sustainable unemployment rate" ?
What does that have to do with the arterial level bleeding of full time jobs in our economy?
Are you trying to tell us that the blood bath in full time jobs is good? (as December layoffs accelerate)
I would define a sustainable unemployment rate as one that is close to the noncyclical rate of unemployment. I would estimate the current noncyclical rate of unemployment to be in the 4.25 - 4.75%. The noncyclical rate of unemployment is generally regarded as one that would not be acceleratory to inflation.
I would not classify the current loss of jobs as a bloodbath and I think that some job loss was needed to restore some slack in the labor market. Inflation is still a little on the high side, so removing inflationary pressures from the labor market will aid in bringing inflation down.
Another factor affecting the number of people employed is the wave of baby boomers that are currently retiring. A lot of them are completely exiting the labor market while some are moving from full time to part time employment. I think this will continue to affect the labor market for the next decade.
The last thing to look at is that the proportion of people that are experiencing frictional unemployment is about 60% and those experiencing structural unemployment is about 40% of all unemployment. This is reflective of a labor market that is not distressed. If those numbers get flipped, I would be very concerned about the labor market.