The latest Colmar Brunton poll on David Farrar's Curia blog shows the government's in a good space at the moment, thanks to a 5% bump for National. Labour has slid two points while the Greens slid one. This appears to be all down to John Key's popularity as preferred Prime Minister increasing 5%.
On these numbers, National would be on 62 seats, which plus Act and United Future with 1 each gives them a majority of 1. Should the Maori Party survive or at least retain its 3 seats, the John Key led bloc will have a majority of 4.
Of course MMP politics isn't always this simple. David Farrar's numbers assume everyone retains their seats. My guess is that Act will lose its seat at the next election, with the National candidate taking it, while Peter Dunne may survive in Ohariu. As mentioned above, the current ructions in the Maori Party could see all three of their seats lost to Labour. And that's where it gets interesting. If Labour wins back all of the Maori seats (bar Hone's), there won't be the overhang their currently is.
Using the handy MMP calculator from the Electoral Commission's website, if the Maori Party loses all its seats, there will be no overhang and parliament will revert to 120 seats. This means National could govern alone, with 63 seats. Ironically, the death of the Maori Party at the polls could very well deliver Key his third term.