They can change to fix their ASIC - but it takes MONTHS once they have access to the new algorithm - redesign the chip, validate, do a tapeout, test, then *if* the tapeout chips are right order production to go into the QUE when space comes open.
I can see Bitmain trying to do this perhaps ONCE, I doubt they'll try after the first time due to the COST.
Makes sense.