Such a future is envisaged in the Good Friday Agreement, via referenda on both sides of the border, and public-opinion surveys and population trends suggest that this is more than just a remote possibility. For one thing, long-term demographic changes make it likely that Roman Catholics in Northern Ireland, most of whom identify as Irish nationalists, will soon become the largest religious group in the statelet, which was crafted in 1921 specifically to have a pro-British Protestant majority. And sentiment appears to be moving in that direction: Last month, for the first time, a survey found that a majority in Northern Ireland was in favor of reunifying, albeit only by a margin of 51–49. (The poll was, notably, carried out by a company owned by Michael Ashcroft, a former senior official in Britain’s Conservative Party, which is officially unionist.)

Read: Brexit and Britain’s Northern Ireland déjà vu

The notion has become so mainstream, in fact, that Peter Robinson—a former leader of the hard-line Democratic Unionist Party (DUP) whose dedication to preserving Northern Ireland’s place in the U.K. once led him to co-found an armed paramilitary group—publicly stated last year that unionists like him would be wise to start planning for a vote, and to be prepared to respect the result. “I don’t expect my own house to burn down,” he said, “but I still insure it because it could happen.”

It is hard to overstate what a remarkable shift this is. And yet, at the same time, it is difficult to understate how ill-prepared everyone is for it to actually happen.

How, practically, would Ireland be reunited? What flag would fly over which buildings? Would residents of Northern Ireland still be able to claim both British and Irish nationality? Would a united Ireland be a unitary state under Dublin’s present structure, reversing (or, some nationalists might say, avenging) Britain’s partition of the island almost a century ago, or would it be a newly federal country, with the north retaining its separate parliament, police, and administration and London standing as guarantor of the interests of Northern Ireland’s unionist population, as Dublin has stood for Northern Irish nationalists?

Such questions are already being debated quietly in many unofficial forums and back rooms, yet neither Dublin nor London is involved. The British government is consumed by Brexit, while Ireland says its priority is to protect the Good Friday Agreement (“The Irish government very firmly does not see Brexit as a vehicle for achieving a united Ireland—they are separate and distinct issues,” a government spokesman said). Even the Northern Irish assembly and executive, which have an array of their own powers, have been suspended for the past three years because of a standoff between the DUP and Sinn Fein, the main nationalist party. As far as is known, no unionist politician has yet joined any of these private conversations about Irish unity. And even those who are prepared to at least consider the possibility remain deeply skeptical, not only of arguments about identity and sovereignty, but of the practical benefits as well.