The Prime Minister's absolute rejection of ever reconsidering a new capital gains tax (CGT) sets her up for an overwhelming election triumph in 2020.
Not only has Jacinda Ardern's decision eliminated National's best issue, the way it was announced has almost certainly secured both NZ First's return to Parliament and its preference for Labour for a second term.
Moving towards the election, National will argue that a vote for NZ First is a vote for Ardern, which will be true as far as it goes. But just as truthfully, as more centre voters recognise National's position as hopeless, Winston Peters or Shane Jones will be able to pitch that a vote for NZ First is a vote to keep the Greens out of Cabinet and major social or economic change off the table.
Everything about last week's CGT announcement was pure theatre, of course.
Ardern never needed Peters' support to promote a CGT in 2020.
From the get-go, there was never any intention to introduce a CGT this side of the election and there is no immediate need to legislate for one to be introduced in 2021/22 either.
It would have been perfectly possible for Ardern to have announced that the current Coalition would not be legislating for a CGT but that her Labour Party would campaign for one to be put into law for 2021/22 in the first 100 days of a new Labour-led Government.
Her decision to permanently abandon the idea suggests she recognises that, for all her popularity and ability to emote, she does not have the knowledge, background, intellect or skill to win a contentious policy debate.
Even more than John Key and Helen Clark before her, the decision indicates that she intends more to preside and maintain her own position than take risks to emulate Jim Bolger, David Lange or Robert Muldoon in building a policy legacy of some sort — whether substantial infrastructure investment, major social or economic reform or historic moves on race relations.
Those on the left who lament both the CGT decision and what it reveals about Ardern and her Government ultimately don't count. For the next little while they can vent their anger on Twitter but Ardern knows they'll be voting Labour or Green in 2020, and either tick serves her re-election.
The more important consequence is maintaining NZ First's viability and Labour's own support among West Auckland small-business owners, the so-called "white van" vote.
All three parties in the current administration win from the CGT decision.
National now needs to face facts: it and Act are close to 20 points behind the three governing parties.
Bizarrely, some on the centre-right seem to take comfort from the most recent 1 News Colmar Brunton poll — completed before Ardern took the CGT off the table — putting National and Act on 41 per cent. They seem to overlook the fact that this puts them a full
17 points behind Labour, NZ First and the Greens, who were on a combined 58 per cent.
To put this in perspective, gaps of more than 15 points between opposition and governing blocs are exceptionally rare in New Zealand.
Were such a result to occur on election night, it would sit alongside the two worst political debacles in living memory.
Recall, back in 2014, when David Cunliffe led Labour to its disastrous 25 per cent result, the combined support for Labour and the Greens was the same 17 points behind the governing parties.
Even in 2002, when Bill English led National to a diabolical 21 per cent, the gap between National, Act and Christian Heritage on one hand and Labour and its support parties on the other was just 22 per cent.
Add United Future for the centre-right — as was assumed was its preference at the time — and the gap was only 15 points.
Key's triumphs in 2011 and 2008 were settled by 12 and four points respectively. Clark, the Alliance and the Greens dispatched Jenny Shipley in 1999 by around 14 points.
In the previous 50 years, even before MMP, election-night gaps between the left and right of the current polling magnitude were unknown, with the exception of 1993, when Labour and the Alliance thumped National by 18 points but were nevertheless denied power by the rules of first past the post.
By and large, National MPs remain in denial about how hopeless their position is, especially following Ardern's CGT move.
They misunderstand that, in a country that is generally content, Ardern's very flakiness on any substantial policy matter is one of the Coalition's strengths.
That her every utterance is devoid of content and that her Government has no meaningful policy programme is exactly the way the median voter likes it.
Sadly for centre-right voters, it looks as if National will need to repeat its trauma of 2002 and Labour's of 2014 before it wakes up to the magnitude of the task and difficulty of the decisions required to become a viable alternative government again.
• Matthew Hooton is managing director of PR and corporate affairs firm Exceltium.