In recent weeks, a wave of good policy news has seemed to cement many of the Obama Administration’s accomplishments into place, all around the same time. There were wins at the Court for the Affordable Care Act and marriage equality and a nuclear deal with Iran. Dodd-Frank just turned five, and its most celebrated component, the Consumer Financial Protection Bureau—which originated in this very journal—just landed a $700 million fine against Citibank for fleecing its credit card customers. On the heels of new EPA coal regulations and a U.S.-China climate accord, a deal at this December’s international climate meeting in Paris could amount to real progress against climate change. In light of this long list, immigration reform is a conspicuous outlier. A lasting solution to America’s immigration problems will be a job for the next president, and when a serious legislative debate does finally take place, it won’t resemble those of the past. The issue is changing before our eyes.

The familiar argument over comprehensive immigration reform is really two arguments about two groups of migrants: those attempting to enter, and those already here. For obvious reasons, the categories aren’t totally separate: Every successful member of the first group becomes a member of the second group. But it’s morally intuitive (to most people, anyway) that a distinction can nonetheless be made. The political theorist Joseph Carens, a leading scholar on the ethics of immigration, uses the term “social membership” to capture this intuition: immigrants who have resided in a host country for long periods of time develop relationships which structure their plan of life. This social membership, which is determined (roughly) by length of residence and the deepening social ties that implies, carries moral weight. “If people have lived here peacefully for a number of years, the fact that they violated some law in coming is not as important as their ongoing social membership,” Carens explained to the Washington Post in 2013. “That’s the main argument for why they should be able to stay.”

This is the basic impulse behind calls for a path to citizenship, which is the key component of any comprehensive immigration reform deal worthy of the name. Advocates of a path to citizenship seek to acknowledge social membership by making it official—by turning de facto members into de jure members. The common response to this demand forms the basic structure of the compromise: that in exchange for a path to citizenship, border security be enhanced. From conservatives’ perspective, the logic of the deal is: Fine, we’ll come to terms with the undocumented immigrants who have made lives here, but no more. From now on, the influx is supposed to stop.

This trade-off has structured mainstream reform proposals for years. Its political logic assumes a trade-off enabled by conditions of heavy migration and border insecurity. But now, those conditions are changing. Better surveillance technology and increased manpower at the southwestern border, combined with improving economic conditions and a declining birthrate in Mexico, have reduced the number of crossings and increased the percentage of apprehensions. And a new study finds that total migration from Mexico has dropped almost 60 percent from its peak during the George W. Bush Administration—the last time a comprehensive reform deal came close to passing.

The study did not distinguish between legal and illegal immigration, but it confirms a trend that changes the political logic of immigration reform: The border is more or less secure. The wave of migration feared and denounced by immigration restrictionists is a thing of the past. And so the other half of the immigration deal—citizenship in exchange for border security; status for residents in exchange for closure against entrants—is transforming. It’s impossible to know how this will play out: Republicans may demand ever-greater security, holding out for the quixotic demand of border closure. They might find something else to demand in exchange for a deal. Or, with their border security bluff called, they might be backed into a corner, stuck with an unpopular opposition to the claims of social membership. Whatever happens, the debate will not be the same. And without the countervailing claim of border security, the claims of social membership will gain even greater urgency next time around.