Interesting times.
Sounds like 6 of VBs E-Jets are NZ bound before too long. Not sure how 'regional' they'll be flying though. I paxed on one of these things the other day, and from a passenger comfort point of view, I think they beat an ATR or Dash hands down.
As has been stated, it will all come down to the public's willingness to pay a 'jet' premium. Many of use look straight to the bottom line when booking a flight, but I'm not convinced this is the case in the world of the frequent business traveler.
Having said that, I haven't traveled on the newer turboprop options being considered by Air NZ, and numbers-wise I think the new Q400 would be hard to go passed (provided they've ironed out the quality problems of the original design).