The first article you reference actually talks about increases to many destinations including those where Jetstar are going to;
Stuff 11.11.14: Other towns experiencing increased demand, including Kerikeri, Whangarei, Tauranga, Hamilton, Rotorua, Gisborne, Taupo, Wanganui, Palmerston North, Blenheim, Hokitika and Timaru, were the winners of today's restructuring.
None of the towns that had services cut have had the benefit of a Jetstar service. I wonder why.
So far as the second article goes, do you seriously believe the ATR purchase announced in Nov 2015 happened as a reaction to Jetstar. These sorts of decisions are not made over night