I see the problem as reversed. A good number of retired health workers are ready to come out of retirement to help. A resp. therapist is trained on many things not that relevant for this one critical illness/situation. Many can be temporarily relocated city to city as the apexes move place to place.
At one university hospital surgical residents are being trained to do the tasks of an ICU nurse.
We just don't know how many respirators will soon be needed in NY or elsewhere before production ramps up. It's now thought the virus transmits by aerosol as well -- you can breathe it out and in. The camp that thinks large areas of the U.S. will be spared are IMO engaged in magical thinking.
A UNC corona virus expert said the word of a pandemic was spread here when China announced community transmission, well before the first US. case We did nothing. He also spoke about several other corona viruses in bats that could easily jump to humans.
Yes, all of that is quite possible. I've no idea how many retirees are coming out of retirement. Is it thousands? Do we have any data beside the odd news story here and there? I've also no idea how quickly someone can be trained, and brought up to the needed skill level, under these conditions. I know China, by the sheer size of its population, had the ability to surge a great number of doctors, and nurses, into Wuhan. I don't see us as having that capability. I hope I am wrong, but I don't believe I am.
Our health care system has been taken down over the years. We once had a law - Hill-Burton - that mandated 4.5 beds per 1000 people (in rural areas it was 5.5 beds per 1,000). That capability has been taken down. Community hospitals stood at 7,000 in the mid-1970s, dropped to 5,000 in 1999, and in 2009 to 4,897. The Hill-Burton standard of beds per 1,000 dropped to 3. As of 2000, the total U.S. public health-care workforce was 448,000, which was 50,000 fewer than in 1980. Looked at per capita; in 1980, there were 220 public-health workers per 100,000 U.S. residents; but in 2000, this had fallen to 158 per 100,000. A great many of those will have retired by now, or have passed on.
We've already a shortage of nurses, to speak nothing of ICU nurses; you can read the stats, from the American Association of Colleges of Nursing (AACN), on that here: https://www.aacnnursing.org/news-information/fact-sheets/nursing-shortage
Before the pandemic, there was a serious shortage of ICU nurses; see "The nursing shortage in acute and critical care settings" https://www.ncbi.nlm.nih.gov/pubmed/12473920
and "U.S. hospitals brace for another challenge — an unprecedented shortage of nurses" https://www.nbcnews.com/health/health-care/u-s-hospitals-brace-another-challenge-unprecedented-shortage-nurses-n1167786
As far as the virus being spread via aerosols, I think there is a misunderstanding about
that. It isn't airborne in the sense people thing of. Stat had a great article about
"'If it could easily exist as an aerosol, we would be seeing much greater levels of transmission,' said epidemiologist Michael LeVasseur of Drexel University. 'And we would be seeing a different pattern in who’s getting infected. With droplet spread, it’s mostly to close contacts. But if a virus easily exists as an aerosol, you could get it from people you share an elevator with.'"