I had 50 checkride signoffs in 4 years as a full time CFI and not one of those was an American commercial student. I had a lot of Americans who were looking for a PPL or IR and owned their own plane or were members of a flying club. I taught some Chinese commercial students going back over to China to fly. I didn't teach or even come close to teaching a single American student who wanted to be an airline pilot.

I'm not sure why the airlines didn't see that coming with 8+ year upgrade times, 20k starting salaries and constant concessionary contracts in times of profit.