At the risk of repeating what I said earlier...
I was talking about this with a few of my colleagues today, and every sports fan at my work would jump at the chance to follow a Wellington NRL team - whether it's relocated from Sydney or home-grown.
It's a chance to be involved in the best RL comp in the world.
I think the thing here is that it would be us against the Aussies - us Kiwis just love the chance to get one up over our trans-Tasman cousins. The parochial mentality comes in more when you look at domestic sports competitions, where there's a heap of NZ teams battling amongst each other, with no Aussie team to rally against.
Kiwis love getting behind around any team that's playing against an Australian-based one. Look how we cheered for Ireland in the RWC!
It wouldn't matter if the side has bugger-all NZers initially - so long as the juniors can make their way through, that would change over time. (Anyway, the Warriors have shown that we can adopt the likes of Steve Price etc as one of our own..)
Actually, due to parochial (especially NSW v Qld) Australian sentiment I think there'd be LESS resistance to a relocated Sydney team from NZ than there would be in Brisbane, Perth, or the Central Coast...