Just testing people for Covid 19 to isolate the positive cases and contact trace isn't something which could be done in a few weeks, because you'd have to test the whole country, and we don't yet have an adequate number of test kits or the capacity to process them.
In addition to that, somebody who tests negative today could test positive tomorrow.
I'm sure some people would say take it industry by industry, essential ones first. That's more feasible, but they could still contract the disease in the time between testing and even getting the results.
If the standard was going to be let those who are positive but don't seem ill go back to work, people who are still contagious could go back to work, spreading it to others. Would the authorities have to take the word of people testing positive who are saying they never got ill at all?
The antibody testing would take care of that to some extent. However, how long will it take to produce the tests and antibody test and process and get the results for everyone even in essential industries? It's certainly not a matter of a couple of weeks.
The caveat is that the paper I saw cautioned that the antibody level goes down after a while, and they don't know how long any immunity would last.
IF, and it's a big if, people were sent back to work in essential industries, they'd have to be wearing masks, as they do in East Asia, and they would need one for every 8 hours of use. Those masks should be available before you go sending people to work.
Meanwhile, while all this preparation is going on, the hospitals are going to be overwhelmed, and it's not just Coronavirus patients who are going to die, and not just the elderly. People with life threatening or chronic conditions are not going to hospitals for fear of exposure. Those deaths are usually not counted, but it's beginning to be done, and the results are worrying: the deaths from the same, say, week last March to this March is exponentially larger, much larger than the number of documented Coronavirus deaths.
As for indefinitely quarantining anyone over, say, 60?, who is going to take on that responsibility? How should that be done? Putting them in nursing homes is a recipe for disaster.
So it's clear, I don't have the answer. There are too many unknowns right now.
I'm all for getting the economy going again, but I don't see how it would be possible within a few weeks. Trump is being very irresponsible, imo, to call for that.