Blocky CaptainGrumpy has a point even tho he has argued it very poorly and over-stated its importance.
ODIs and T20s do pay the bills for Test Cricket. That applies everywhere.
However, people will watch Test cricket if their team does well. I have seen this first hand with all my fairweather Indian cricket fan friends. Couldn't give a **** about cricket till we won the T20 WC and suddenly became really good at ODIs. We then climbed to number one in Tests and won a World Cup and it was all they could talk about. Then 8-0 happened, and by 2013 no one really gave a **** about Indian cricket anymore outside of the IPL.
It was sad to see, but that's basically how Joe Public rolls. They aren't cricket fans, they are patriots who view Cricket as a means to feel good about their country.
Which is why now, with this wonderful side developing, NZ should be playing as many Tests as they possibly can. They will win a lot, Joe Public will tune in on TV, show up to the grounds, and open their wallets to be a part of this feel-good experience, and in the process NZ will also uncover a bunch of new Test Cricket diehard fans. Sponsors will sign up, money will flow in, and Tests will be in vogue.
Eventually, a time will come when the NZ side slips back down the rankings. Joe Public won't care anymore, but atleast he will remember a time when his side was one of the best in the world, and the new die-hards will still be around, posting in this doom and gloom thread till the next wave of awesome players.
Playing more ODIs and T20s now is such a waste of the great talent they have. They really should be cashing in on the brilliance of the Test side.