Agree. The big question is 75 current 737's vs the number of A320 series ordered.
Last year QF noted "94 purchase order rights spread over a at least a decade" - iirc QF earlier this year extended the A220 order to 29, and I will assume those extras came from these 94 purchase rights. However, that's still scope for, over the long term, to replace all the 737's with A32x series (and yes, possibly some A220's). The mix of 320/321 that we end up will be interesting.
However since they say "... over at least a decade" says this is VERY long term, and the 737's will be with us till at least 2030 if not later. Clearly they will replace the older ones first, but still by the time they go the "youngest" 737's in the fleet will be near 20 years old.
I actually had a great conversation with a 737 FO on a recent flight about exactly this point (he wants to move to the 330 as a path to the 350 for his own reasons) but the 737 tech crews are both aware of the A320 series current shortfall vs the number of 737's. Additionally, of course, from the QF mainline pilot POV, the 220's are bad news as they're operated by QFLink (whoever has the contract..) and at lower pay rates. Now sure, the 220's won't replace many 737 routes, but given the bigger number of 220 orders vs the 717 fleet, and higher capacity of the 220's (137 vs 110) and the longer range, clearly QF see opportunity to trim some routes of 737 capacity for 220 - perhaps adding frequency to some routes that wouldn't support 2x737 for example.
Whatever it is going to be, we'll still have a majority of 737's still in the fleet for at least the next five years, and probably past ten....
