As last week’s momentous assembly election result sinks in, the DUP and Sinn Féin are having a wobble over Arlene Foster’s future.

The DUP had insisted its leader would not stand aside as first minister, as demanded by Sinn Féin, pending an inquiry into the Renewable Heat Incentive (RHI) scandal.

Now the DUP says stepping aside would be “a decision for Arlene” – one of those deathless political phrases, such as “my wife has complete confidence in me”, that can presage a swift departure.

Meanwhile, Gerry Adams has said Foster can make an early return if the inquiry reports in “modular form” – a new phrase to Northern Ireland. Sinn Féin’s argument for excluding Foster was that there must be no political interference in the RHI inquiry, so it was daring of Adams to apparently interfere with it. A cynic might suspect Sinn Féin of wanting to keep Foster around, given her success at raising the republican vote.

But I digress – it so easy to get drawn into the details at Stormont, or to fall into the trap of the internal settlement, as a republican might say.

The true significance of last week’s election is that Sinn Féin has moved on from the temporary partitionist parliament. It has to pretend otherwise to some extent – many nationalists still want regional government to work – but as far as Sinn Féin is concerned, Stormont has entered a new phase as a means to Irish unity’s end.

For the first two decades of devolution, Stormont’s purpose to that end was to put Sinn Féin in government on both sides of the border.

Big picture

Now Stormont can serve directly to remove the border – by triggering a border poll, exploiting Brexit, or sustaining a crisis that draws Dublin into Northern affairs. That may or may not involve a bit more governing with unionists, but no matter. The big picture is in play.

A distinction should be drawn here between the assembly and the executive – the latter might never return but the former can limp on indefinitely. Northern Ireland has often had an assembly with no executive at times of crisis, because the British government tends to see this as the solution to a crisis. “Transitional assembly”, “shadow assembly” and “consultative assembly” are phrases we may hear again, each implying a path back to devolution.

Such an arrangement would be the best of both worlds for Sinn Féin. An assembly provides an arena, whatever happens to the executive. Brinkmanship need not be relegated to country houses in England or bland office blocks in Belfast, as in previous crises. It can retain the full infrastructure of public life.

The DUP may continue to disgrace itself in an assembly, further boosting the forces behind last week’s election. More interestingly, unionism may learn some humility and not veto motions, acts or private member’s Bills on landmark issues such as same-sex marriage or the Irish language.

But either way, unionists will be demonstrating their new minority status on Stormont’s benches. The centrist Alliance party, which holds the balance of power, is “presumed unionist” although officially unaligned. It does not take much to shake that assumption, however, as shown by the 2012 flag row at Belfast City Council – another non-executive assembly where Alliance is the meat in a DUP-Sinn Féin sandwich.

Border poll

Under the Belfast Agreement, the secretary of state may call a border poll if it seems likely that nationalism might win.

The test for this is undefined but a nationalist majority in the assembly is usually cited. While we are years away from that eventuality, if ever, unionism would not have to lose many votes to muddy the waters.

Of course, once this occurs to unionism, it will veto everything and become even more off-putting to everyone else – a win-win scenario for republicans.

Anything less than full devolution means a degree of direct rule from London, enabling Sinn Féin to demand input from Dublin.

The UK government repealed its power to suspend Stormont under the 2006 St Andrews Agreement, so having to restore it can be portrayed as bad faith or at least a movement of the goalposts.

Sinn Féin began moving its goalposts in advance, as the election results came in. Party representatives repeated the phrase “joint stewardship” – an even fresher coining than “modular inquiry” – along with claims that St Andrews allows for it. These claims were nonsense. As Prof Rick Wilford of Queen’s University Belfast told the BBC: “There is no textual basis for joint authority.”

But Brexit has created a political basis for Dublin intervention, along with a slow-motion, all-Ireland crisis that can be synchronised to problems at Stormont.

Enda Kenny has already said he will speak for the North in Brussels in the absence of an executive.

Early last decade, when Sinn Féin began abandoning its euroscepticism, it described the European Parliament as “a site of struggle”.

It is always about the struggle for Sinn Féin, in every parliament. Stormont is never an exception.