Oddly enough this also caused similar issues in classical orchestras - in the 90s a bunch of top flight Eastern European and Russian musicians raised the bar of orchestras in places like NZ, with the side effect of having fewer seats for younger musicians to move into.
It reminds me of ex-Soviet chess players. The emigration of so many good grandmaster-level players diluted the market, and unless you were in the absolute upper echelons (like Kramnik, Karpov, or Kasparov), you pretty much had to supplement your income by teaching on the side.