I've visited Norfolk Island many times and am very sorry this has happened.
Some years ago NZ used to fly there twice a week, but then reduced it to once a week. That in itself was a pity as it meant that NZ residents of Norfolk (approximately one third of the population) couldn't have short trips to NZ and have rellies visit Norfolk.
It also meant that some people went to Norfolk for shorter holidays. I used to enjoy a 10 day visit - 7 days too short, 14 too long.
But I doubt many NZers will bother to visit if they have to go via Sydney or Brisbane. I won't!
Nor would I bother if someone introduced smaller planes. Entry into Norfolk could be hairy at times if the weather closed in and there is no radar to help.
Airlines servicing the island from Australia, using older and smaller planes and inexperienced pilots, often couldn't get in when NZ was able to do so with no problems.
So, yes, I'm sad at this development and I'm sure that many others will be too, not least the Norfolk Island residents with links to NZ.