There are 62 F100 aircraft currently on the used aircraft market.
This figure does not include the 74 AA F100 fleet.
It now appears the AA F100's are to be retired as they fall due for heavy maintenance over the next few years. I would think that most of these aircraft would then be parted out or scrapped.
For Apacau:
I think the F100 had a nominal nil wind range of 1500nm with the standard Tay 620 engine. Forgetting about ETOPS considerations a trans tasman scheduled service would be very marginal in my opinion. Add the possiblity of an engine shutdown and or depressurisation into a headwind and it could be very marginal.
From memory I think the aircraft is certified for up to 109 pax. With full tanks (I guess 10,500kgs) I think the a/c was good for approx. 88 adult pax with bags and nil freight.
No doubt a F100 driver will comment.