If you are making the distinction between 'Mainline' Qantas and Jetconect then your statement is not correct.
The A330 service QF25/26 MEL-AKL-MEL is being replaced by a 'Mainline' 737-800.
Don't get me wrong, I'm not at all happy about the continual shrinking of this once great airline but the particular change you refer to is not entirely correct.
ps. And I think 'Mainline' still do the Queenstown services as you suggested.