The Herald article on the subject kind of suggests that FFA and Welnix will be ganging up on NZF, which I personally have no problem with. I wouldn't be happy going down the "NZ Phoenix" route, although it might be more convenient for me with more Auckland games. But they have a point - they want a 4.5 million market, not a 450,000 market, and getting a solid following in AKL and Chch is vital for that.
Ultimately though I think the biggest issue with becoming the NZ Phoenix is it pretty much ensures no future expansion into the NZ market, and IMO the single biggest thing that could be done to increase interest and visibility in the A League across all of NZ media and public would be to create a 2nd kiwi franchise and get some sweet derby action going. That might still be years away but that should be a long term goal for all stakeholders.