In this part of the world 737-500s have never been popular. Ansett NZ were going to start with 735s until Ansett made them use 146s. The only 735 here was one at Air Pacific.
If AirNZ is shopping around for planes for regional centres, would the smaller 735 be any use? About 120 seats in same configuration as AirNZ 733s.
Complaint about shrunk aircraft is that they are often as expensive to operate as the full sized plane, minus the seats for revenue. I think Boeing sold more 735s than they expected, and 735s have worked in the fleets of BA, AF, LH and United. If 735s give you a break even for some cities that is lower than for a 733, this would be worth it?