Seattle will want a QF order/replacement for whatever follows the MAX so if they need to lose cash on this order then so be it. Otherwise they have lost a narrow body customer for a very long time.
I can’t see the A320N getting a series 2, so when 2050 rolls around and Airbus and Boeing are rolling out the next gen narrow body, bit hard for QF to swing back Boeing if they have a sole fleet 200 A32X machines. I’d expect very little in the way of crew conversion training for A320 to whatever replaces it, however can’t say the same about Boeing.