National's Nightmares

According to the Roy Morgan poll (published 7 May), there's been 'a large fall in support for National (42.5%, down 6%) now well behind a potential Labour/Greens alliance (45.5%, up 5.5%).' But they wrongly draw the conclusion that the poll results imply 'that the potential Labour/Greens alliance would be elected.' Assuming that the Conservatives do not win an electorate seat and the Internet party doesn't coat-tail in with Mana, then National would have 53 seats and would be able to form a government with NZ First support (7 seats) plus support from United Future and ACT (assuming the latter two retain their single seats). Labour and the Greens combined would have 56 seats, and so they too would be able to form a government, but only with NZ First's support.
Even if the Internet Party and Mana successfully form a pre-electoral arrangement and they gain a total of 3 seats between them, the numbers would still add up for a National-NZ First coalition (with support from UF and ACT), but with a wafer-thin majority of 61 out of 120 seats. (I'm assuming there's no over-hang). So, it could go either way (National- or Labour-led government), but all would depend on Winston Peters!

Could we end up with no clear winning coalition and a deadlocked parliament after the next election? Yes we could, and here's how...
Suppose the Conservatives steal votes away from National and NZ First, but neither the Conservatives nor NZ First gets over the 5% threshold, resulting in, let's say, 9% of the party vote 'wasted'. At the same time, National dives to 44%, Labour gets 30.3% and the Greens 13%. The remaining one-seat parties (UF, ACT, Maori and Mana) all get around 1% each or just under and retain their one electorate seats.
That gives National 58 seats; and then Labour 40, and the Greens 17 (58 between the two them).
National can rely solidly on ACT and UF for their support, but they then only have 60 votes in total in a 120-seat parliament. All eyes would be on Te Ururoa Flavell as the sole member left from the Maori Party. He has the choice either to support a National-led government with a wafer-thin margin of one vote (and hence his party faces political doom for doing so), or perhaps to abstain on confidence votes and let National carry on as a lame-duck government fighting for every piece of legislation. If he preferred to support Labour (as I suppose he does), then that too would only have 60 seats.
Under such circumstances, the incumbent National-led administration would presumably stay in office for the time being, but it would have great difficulty passing legislation, and may be stymied when it comes to supply. What could be worse?