There’s a common refrain on the American left right now: “The kids are alright.” The student activists who launched a gun control movement in the wake of the high school massacre in Parkland, Florida, have given hope to progressives that the future they desire may yet emerge from the dark age of Trump. Encouraged by the teens’ example, some on the left want to accelerate their political rise by lowering the voting age to 16 nationwide. Others have called for millennials to overthrow their likeminded but ossified elders. “My message, as an aging Gen X-er to millennials and those coming after them, is: Go get us. Take us down,” Tim Kreider wrote last week in a New York Times op-ed title “Go Ahead, Millennials, Destroy Us.” “I for one can’t wait till we’re gone. I just wish I could live to see the world without us.”

But it would be a mistake for Generation X and Baby Boomer progressives to sit back and assume that generational turnover, all on its own, will usher in the more just, less violent America they’ve long hoped for.

There’s no guarantee that young people will remain politically liberal—by today’s standards—as they age, though the evidence favors it. “On an individual level, of course, many people’s political views evolve over the course of their lives. But academic research indicates not only that generations have distinct political identities, but that most people’s basic outlooks and orientations are set fairly early on in life,” Drew DeSilver of the Pew Research Center wrote in 2014. “Americans who came of age during the Truman and Eisenhower administrations, and are now in their 70s and 80s, have fairly consistently favored Republican candidates, while those who turned 18 under Bill Clinton and his two successors have almost always voted more Democratic than the nation as a whole.”

Millennials are undeniably more progressive than their elders: In 2016, 55 percent of them identified as Democrats or Democratic-leaning. But their coming of age as voters—millennials between the ages of 22 and 37, says Pew—hasn’t led the country to embrace liberal policies across the board. Americans do increasingly accept same-sex marriage and marijuana legalization, but support for gun rights has increased over the past two decades. Views on abortion have barely changed over four decades. Just because the conservative Silent Generation is dying out while millennials are ascendant doesn’t mean that public opinion will shift leftward on all social issues. Political change doesn’t follow such a predictable pattern. And when new issues arise in the decades to come—like how to regulate artificial intelligence—who can say what the liberal position will even be?

So we progressives over 40 shouldn’t call for our own political destruction just yet, as Kreider does. He asks millennials to take down “all those cringing provincials who still think climate change is a hoax, that being transgender is a fad or that ‘socialism’ means purges and re-education camps. Rid the world of all our outmoded opinions, vestigial prejudices and rotten institutions. Gender roles as disfiguring as foot-binding, the moribund and vampiric two-party system, the savage theology of capitalism—rip it all to the ground.”

I agree on all counts. Cheer on the kids, by all means, but beware that their revolution might not include us. And young people’s political convictions and ours aren’t always the same; the next generation won’t necessarily just get rid of the stuff that our political rivals like. Once they have power, they might not spare our favorite causes—no matter how hard we cheer. (For instance, Kreider admits he’s “creeped out by the increasing dogmatism and intolerance of millennials on the left.” I am, too.)

Young people aren’t the only ones with political energy liberals can use right now. Emma González and David Hogg, of Marjory Stoneman Douglas High School in Parkland, have gotten a lot of airtime since the mass shooting. But as historian Lara Putnam and sociologist Theda Skocpol show in a recent article in Democracy, middle-aged and retired suburban women are the grassroots leaders of the left, those doing the day-to-day local work of organizing and advocacy in support of core progressive priorities. Between now and the 2020 elections, Putnam and Skocpol write, resistance to President Donald Trump and the Republican Party “will look like retired librarians rolling their eyes at the present state of affairs, and then taking charge.”

Gen X, which still has not elected a peer as president, eventually will lose its political influence. Society advances one funeral at a time. But I’m not ready to be buried just yet. Like many middle-aged progressives, I only just broke out of my stereotypical apathy and became more invested in the minutiae of politics. The kids show promise, but progressives still have to work between generations to build a common platform and get it enacted. By sitting by and waiting for a new generation to come of age, we won’t realize the utopia we dreamed of in headier moments of the Bill Clinton or Ralph Nader or Barack Obama campaigns.

In time, the kids will fight a two-front political war: against their predecessors on the one hand, and against the generation that’s just learning how to walk and talk. The kids will get old, too, and they’ll curse their failures and cling to their accomplishments, as their children rise up to seize it all—with or without their elders’ permission.