As someone who has both crafted and professionally scoffed at headlines in many ways through many elections, I'd like to just reassure everyone, right now, that yes, your instincts are correct: most of the ones you'll see after the Iowa caucus will be absurd and should be ignored.
What specific forms will this absurdity take? Let's go over a few of the more likely possibilities, just so we don't have to bother with them after fact. Keep in mind that many outcomes are possible. The same general rules can be applied to those, as well.
One of These Two People Is the Next President!
Let's just get this out of the way: the Iowa caucuses are ridiculous. We'd probably be better off dropping stones in heaps like the ancient Athenians. They're also not especially predictive when it comes to general election nominees. New Hampshire is also pretty terrible. In fact, there's been a lot of talk lately about a South Carolina "firewall," where the Republican Party could rein in the crazy that has broken out in the first two contests.
But Iowa in particular is just... infamously bad at picking winners.
John McCain came in 4th the year he won the Republican nomination. That was 21 points behind Mike Huckabee. McCain did win New Hampshire, though--as he had in 2000, when he lost the nomination to future president George W. Bush.
In 1996, eventual GOP nominee Bob Dole beat Pat Buchanan by just three points. Pat Buchanan, people. Then, Buchanan actually won the New Hampshire primary. Surprisingly enough, Dole had won the caucus far more decisively in 1988, when he didn't pick up the nomination.
That year, Vice President George H.W. Bush finished two places and 19 points behind Dole before going on to win the presidency. Like Dole, Bush won the caucus eight years before the nomination, when he edged out Ronald Reagan by about two points. Reagan was, of course, elected president that year.
Bill Clinton came in fourth--two spots below "uncommitted" and with just 2.8% of the vote--the year that he became president-elect. Between those two events, he also lost the New Hampshire primary to Paul Tsongas. (Tsongas had placed higher than Clinton in Iowa, too.)
Michael Dukakis came in third the year he won the nomination, behind Dick Gephardt and Paul Simon.
Jimmy Carter came in ten points behind "uncommitted" the year he won the presidency.
And, poor ol' George McGovern came in a full 13 points and two positions behind "uncommitted" the year that he won the nomination.
To be fair, the Iowa caucus is not meaningless. It awards a handful of delegates and plays an important role in winnowing crowded fields. But this idea of momentum that will spread far and wide in the coming days is more often than not nothing more than a really silly myth. In real life, voters aren't sitting around saying things like, "Well, Iowa voted for this guy, and they seem pretty together..."
Republicans Can't Stop Trump!
Imagine, for a moment, that it's July. Donald Trump is heading to the Republican National Convention having already secured the nomination. In order to do that, he probably had to win large, winner-take-all windfalls in establishment-friendly states like Ohio, Florida and Arizona. (Note that Florida and Ohio have perfect records of backing nominees since 1976, even though Florida has generally held its contests before a consensus has emerged.) In many other states, Trump had to win bonus delegates by hitting thresholds as high as 50%. It's a little hard, looking back, to believe that his road to 1,237 delegates all started with that handful back in Iowa, but Trump's ground team of "really great people" eventually beat the Republican Party at its own game and emerged victorious.
Sounds to me like there were a lot of places where the Republican Party could have stopped Donald Trump after he won Iowa and/or New Hampshire. Have you ever seen him hit 50 in a national poll? I haven't. A single, strong establishment challenger could erase an early Trump lead in just one or two states.
Will one emerge?
As always, Ted Cruz makes things more difficult. It is entirely possible that in a three-man race between Trump, Cruz and a third candidate who has won the role of establishment challenger, Trump would secure the nomination or score a plurality that the GOP wouldn't dare deny. It's also entirely possible that no establishment challenger manages to break through in time to stop him. But "entirely possible" and "sure thing" are pretty far apart in this case.
One caveat: if Trump significantly over-performs his polling in Iowa and New Hampshire, this headline would seem to hold more truth.
Hillary in Peril: It's 2008 All Over Again!
Contrary to popular belief, it is not, in fact, 2008. Remember what I said earlier about crowded fields getting narrowed, but momentum not being especially real? This isn't an eight-person race that early contests will whittle down to two. 2008 was. If Bernie Sanders wins Iowa, New Hampshire or both in anything short of blowouts, the headlines will change, but the race won't.
And the unchanging dynamics of this race greatly favor Hillary Clinton. The super delegate and votes-to-delegate advantages that Barack Obama won with Iowa in 2008 are already held by Clinton this round. Clinton's standing in the polls is much better than it was heading into 2008. And two large states haven't been stripped of delegates, as they were then.
What these first two contests will tell us is how Bernie Sanders is doing among his primary demographic. It's no secret that Sanders hasn't had much luck expanding his support beyond a base of white liberals, and New Hampshire and Iowa are two of the five whitest states in the union. So, the first two contests look good for Bernie.
The following six weeks, not so much. Clinton currently leads among nonwhite voters -- who will be mostly absent from the first two contests -- by a whopping 39 points. In order to show that he can compete with Clinton for the nomination, Sanders wouldn't just have to win the first two states; he'd have to win them by very sizable margins.
When Will Bernie Drop Out?
If long odds were going to keep Bernie Sanders out of this race, he wouldn't be in it to begin with.
The conventional wisdom is that primary campaigns end when the money dries up and, in this case, it's probably right. That isn't going to happen to Bernie Sanders anytime soon. His supporters are a famously loyal bunch. They're probably already writing nasty comments below. If he wins Iowa and/or New Hampshire, they will donate. If he loses Iowa and/or New Hampshire, they will donate. If he devours a kicking, screaming infant on live television, "I just donated another $10 to Bernie Sanders," will trend on Twitter.
Again, don't expect the outcome of the early states to actually change the dynamics of this race by much. Remember that, back in 2008, Clinton continued to win states and accumulate delegates long after it became clear that Obama was the nominee. She even won or came within one point of winning the popular vote, depending on how you count it. There's no reason to believe that Sanders' support won't be just as loyal. Even if he loses one or both of the first two states, he'll continue picking up delegates and would still be expected to win a few contests, like in his home state Vermont and places where Clinton is deeply unpopular, like Alaska and Colorado.
It's All Over: Trump Finishes Third