2020 is already shaping up as a two-horse race with a few paddock companions scrabbling for survival.
But 2023 could prove a completely different affair, especially if the Government forges ahead with proposed electoral reforms to lower the 5 per cent threshold at which political parties can make it into Parliament.
There are four potential options for a new stable mate for National - a Christian-based party, Tava's "teal" party, a traditional conservative right-wing party, and a party which can out-do NZ First in tapping into populist angst.
Of the four, there is little doubt the centrist blue-green option is the most palatable for National. Bridges indicated as much when he quipped at the start of his State of the Nation yesterday that his suit was blue, but his tie was green.
The fates of Christian and conservative parties of yore have rather sullied their brands.
Much depends on the leadership of such parties - some have a tendency to turn into Frankenstein's monster at the slightest sniff of power.
But whether the teal option has the highest chance of success is another question.
Tava is not appealing to the traditional Greenie voter but rather the middle class, environmentally conscious who don't like the left-wing policies the Greens pursue.
But the green space is already crowded and mainstream parties themselves have the kinds of policies Tava is talking about.
On the other hand, there are several issues in play that will galvanise the Christian vote, such as abortion reform, euthanasia and the referendum to legalise cannabis.
The biggest protest to hit Parliament this term was over the Speaker's move to scrap Jesus from the Parliamentary prayer.
There is also some appetite for a conservative party. The recent utterances of New Conservative member David Moffett - a former NZ Rugby CEO - shows he is trying to tap into both the conservative and populist spaces.
Moffett criticised PM Jacinda Ardern and Winston Peters for signing a UN compact on global migration, calling them "traitors" and "leftards".
It was a clear play for NZ First voters and there will be some NZ First voters disillusioned by the decision to side with Labour who want another option and will be attracted by such rhetoric.
Much has been made of the likelihood a new party in that space will simply suck voters away from National.
It probably will. But the real question for National is whether a new party can also suck some voters away from Labour, NZ First or the Green Party. After all, there is significant vote swinging between Labour and the Greens.
If it can, it all goes to increase the share of the vote on the National side of the MMP ledger.
So National will sit and watch and poll. If a potential partner - be it Tava's, TOP or Act - gets to about 2 per cent in those polls, the difficult decision will be made.
That decision will involve whether to cut an Epsom-style deal in an electorate to try to ensure the party gets over the line. That will indeed be a cynical step and may backfire.
What could vastly help National's situation in the short term is not necessarily another party rising, but one disappearing.
NZ First's support dropped the moment it sided with Labour, and National will want every one of those votes to revert to its side.
So it now has to decide whether to rule out working with NZ First at all in advance of 2020.
This would be somewhat akin to dumping a lover before they could dump you.
However, there is some fear that NZ First voters who preferred National will believe Peters if he says a National government is an option.
Shunting him out of Parliament increases National's chances of getting into Government alone, and that is an enticing prospect for them. Key had done it twice before, but in very different circumstances.
Peters served his revenge cold in 2017.
