With Cory Booker's exit, the Democratic presidential field has lost another minority candidate, and revived the arguments — pressed by Julián Castro before his own exit from the race — that the whiteness of the Iowa electorate explains the increasing whiteness of the Democratic field.

The debate over Iowa's influence is interesting because, as Bill Scher pointed out recently for Politico, the Democratic Party did several things to make the caucuses less important in 2020: tightening the early primary calendar, creating a de facto national primary on Super Tuesday, relying on polls from Nevada and South Carolina as much as from New Hampshire and Iowa in establishing who qualifies for the primary debates.

Scher argues that these choices worked, based on how much less time candidates are spending in Iowa relative to the past, plus the fact that big spenders like Tom Steyer and Michael Bloomberg have pushed their chips onto later states. And he dismisses the Castro argument entirely, pointing out that Booker and Castro and Kamala Harris all struggled with minority voters as much as with white Democrats, and in diverse states like South Carolina and Nevada and California as much as in Iowa or New Hampshire. Even if you flipped the order of early states so that more racially diverse electorates voted first, the biggest winners would probably be the old-white-guy front-runners, Joe Biden and Bernie Sanders.

Yet even if we absolve Iowans of responsibility for how the field has culled itself thus far, for the remaining contenders Scher's headline take — that "Iowa Matters Less Than Ever in 2020" — might turn out to be completely wrong. Indeed, with three weeks to go before the caucus, it's quite easy to see several scenarios in which Iowa could turn out to be crucial or decisive.

First, it's quite possible that Biden could win Iowa outright, and in doing so basically wrap up the nomination early. Biden's early Iowa swoon has been reversed, he's leading the Real Clear Politics polling average and is even with Sanders in FiveThirtyEight's average, and Elizabeth Warren and Sanders seem headed to war with each other as the race enters the final stretch. Which could set up a de facto replay of 2004, when Dick Gephardt and Howard Dean dragged each other down and John Kerry won an Iowa victory that set him up for an easy glide to the nomination.

Would Biden cruise as easily as Kerry? Maybe not: Sanders has the money and passion for the long delegate-accumulating march, Bloomberg and his billions are waiting, and maybe an Iowa victory would prompt an anti-Biden consolidation (says the pundit who spent 2016 waiting for an anti-Trump consolidation that never came). But given Biden's strength with nonwhite voters, his stable national lead and his perceived electability, if neither of the left-wing candidates can beat him in Iowa, can they really expect to beat him on Super Tuesday? Similarly, if a smooth Indianan in Pete Buttigieg and a cheerful Minnesotan in Amy Klobuchar can't peel moderates away from Biden in Iowa, can a grouchy New York zillionaire really expect to pull it off weeks later? The likely answer to these questions means that if Iowa votes for the former vice president, it may have picked the nominee.

In the second scenario, Sanders could win Iowa, Biden could finish a close second, and the campaign thereafter could quickly become a two-man race — with Klobuchar finished, Warren and Buttigieg fading, and no room for Bloomberg in a polarized left-vs.-establishment contest. The parallel here would be to the Republican race in 2016, when Ted Cruz's Iowa victory made him the anti-Trump standard-bearer, and despite a few Marco Rubio Moments thereafter it was basically Donald Trump against Cruz the rest of the way. In this scenario, Iowa wouldn't have picked the winner outright, but it would have picked the final two and disposed of every other candidate in a single evening.

In the third scenario, Warren could rally to win Iowa — an outcome less decisive for the field's consolidation because of Sanders' money and grassroots strength, but one that would dispose of Buttigieg and Klobuchar and make it likelier that Warren surges past her democratic socialist rival in New Hampshire as well. If Sanders dropped out after that, the rest of the campaign would be a Warren-Biden tilt, in which case Warren would owe everything to Iowa; if Sanders stayed in it could be an easy coast for Biden, who would have Iowans to thank for letting him run against a persistently divided left.

Is it possible to imagine an unimportant or at least undecisive Iowa outcome? Sure. A Buttigieg victory in which the other candidates clump together in a tie for second would essentially leave the current top four intact headed into New Hampshire, which would then have its own chance to play the winnower. (The same might be true of a de facto four-way tie, in which Warren, Buttigieg, Bernie and Biden ended up all within a point of one another.) And a surprise Klobuchar surge to victory might end Buttigieg's chances, while swapping her moderate-Midwestern campaign for his in the top four. In those scenarios Iowa would be extremely important — indeed, campaign-saving — to the winning candidate, but it wouldn't narrow the field, let alone crown a winner.

These undecisive possibilities could certainly come to pass. But all the scenarios where Iowa doesn't matter much — including the more outlandish Bloomberg ones and even the Andrew Yang black swan — depend on a somewhat random-seeming caucus outcome and a national race that's unstable and vulnerable to early-state shocks and Super Tuesday volatility. And the evidence lately indicates that the national race is remarkably stable, that Iowa might be the best and only chance for long shots to shake things up, and that both Biden and Bernie are well positioned to use the caucus to validate their front-runnership instead.

In that case many of the candidates who planned for a long campaign instead of camping out in Iowa would have cause to regret their strategic choices. And despite all the party's attempts to create a 50-state calendar and reduce the caucus state's clout, the Democrats could still discover, well before Super Tuesday, that Iowa has picked their finalists or winner after all.