While there seems no immediate prospect of an Irish general election, and no guarantee that the outcome would propel Mary Lou McDonald into government, there is now the possibility that 2022 will be the year when Sinn Fein becomes the largest party on both sides of the Border.
Recent weeks have seen The Economist, The Guardian, the Financial Times, and others seriously examine the implications of a Sinn Féin-led Irish government.
Sinn Féin is acting in ways which show awareness that some of the world’s biggest companies are pondering what that eventuality would mean for their Irish operations.
Three weeks ago, the Irish Examiner reported that diplomats from other EU countries are contingency planning for a Sinn Fein government — unsurprisingly, given the significance of Irish politics for the EU, and the fact that in several recent polls the party has been 10 points ahead.
Understandably, one of the first questions for informed foreign observers is what this means for Irish unity.
The answer is impossible to fully know at this point, but there is reason to believe that a Sinn Fein taoiseach will damage rather than advance the immediate chances of a united Ireland. That might seem a preposterous analysis. How could the electoral triumph of the party most committed to removing the Border make it harder to achieve that aim?
It is true that there are areas in which a Sinn Fein-led government would be able to advance the cause of reunification.
As one republican recently told me, Sinn Fein would not only be able to direct the apparatus of the State to make planning for a united Ireland a priority but, by changing the political parameters, would be able to force other southern parties to come some way towards it on the issue.
Those parties would then be more effective spokespersons for unity than Sinn Fein, which knows it will always be repellent to most unionist voters in Northern Ireland.
But beyond those tangible boosts for republicans, a radical shift which saw Sinn Fein come to power in Belfast and Dublin would be a symbolic and psychological victory.
The ultimate outsiders — a party which grew out of one of the world’s deadliest terrorist organisations — would have stunned the political establishments in two jurisdictions.
However, elation will not deliver a united Ireland any more than the IRA’s proficiency at ending human life was able to do so — only a referendum will do that. Would a Sinn Fein taoiseach make voters in Northern Ireland who now would vote for the Union consider voting for a united Ireland?
Firstly, being in power in Dublin and Belfast would be irrelevant to the practicalities of calling a Border poll. As set out in Schedule 1 of the Northern Ireland Act 1998, that power rests solely with the Northern Ireland Secretary of State.
The Secretary of State is free to call such a referendum at any point, but is obliged to do so only if he believes it would lead to a vote for a united Ireland.
Despite increased support for Irish unity since Brexit, and significantly more interest in the possibility of radical constitutional change, even republicans do not claim that there is today a majority in Northern Ireland who would vote for unity.
Instead, Sinn Fein argues that the polls which put Northern Irish support at 40-something-pc (other polls put it as low as 30pc) mean that it is at least winnable, on the basis that undecided voters during a campaign could disproportionately shift to support a united Ireland.
And that is where Sinn Fein’s advance in Dublin could be counterproductive. The growing number of centrist voters in Northern Ireland mean that a substantial cohort of constitutional swing voters is emerging, something unimaginable to republicans or unionists a century ago.
Those people who are neither unionist nor nationalist will decide Northern Ireland’s future. What they find most attractive about the south is that it is not like Northern Ireland — there is less sectarianism, it is more prosperous, more outward-looking, and there are different political parties.
If those people liked Sinn Fein, they’d already be voting for them. Not only are they not, but they tend to strongly dislike both the DUP and Sinn Fein, seeing them as tribal reflections of each other, and blame their squabbles for holding Northern Ireland back.
An Irish republic in which Sinn Fein is running the government is far less enticing for many of those people than a state in which the influence of both the DUP and Sinn Fein is diluted.
With a preponderance towards gloom and already feeling isolated, most unionists will be despondent if next year sees Sinn Fein triumph on both sides of the Border. But success in politics can have consequences which are counterintuitive.
Just as the Brexit which most unionists supported quickly became disastrous for the Union they cherish, so Sinn Fein’s rise might not do for the cause of Irish unity what they hope.
Forty years ago, as another southern politician disliked by unionists — Charles Haughey — was voted out of power to be replaced by a very unionist-friendly taoiseach, it would have been reasonable to assume that unionists were universally delighted.
But the Ulster Unionist MP Harold McCusker reacted candidly: “Most unionists, in one and the same breath, are glad to see Haughey away because of what he is, but regret that he is away because he was a very easy target to identify and a bogeyman whom we could point out to our electorate.
"It’s a bit more difficult to do that with Garret FitzGerald…[who is] the acceptable face of republicanism; the soft voice, soft sell — but perhaps much more dangerous.”
If Sinn Fein enters government, the cycle of politics dictates that one day they will leave it. It is in that moment of future defeat, rather than in Sinn Fein’s triumph, that acute peril for unionism may lie.