“Can we stop the shrinking of the segment?” American Honda boss Jeff Conrad said when launching the 10th-gen Accord. “We think we can at least slow it down.”

“When you get into next year and you look at 2018,” Toyota’s Jack Hollis said two years ago when discussing the arrival of an all-new Camry, “I believe with these three products and the excitement they bring back to that segment, I don’t see it falling anymore.” In fact, said Hollis, “When you have new entries and you have a full-year of those sales next year, I think you will see flat to slightly up.”

Meanwhile, Hyundai anticipated that a mere refresh of the Sonata for the 2018 model year would “reinvigorate” the nameplate.

The arrival of the 10th-generation Honda Accord did not slow down the shrinkage. Toyota was incorrect – the midsize segment was not “flat to slightly up” in 2018. And no, the Hyundai Sonata has in no way been reinvigorated.

The rate at which sales of midsize sedans are falling suggests fewer than 1 million of these vehicles will be sold in America within two years, equal to a 58-percent drop in just half a decade.

A projection of 887,000 midsize sedan sales in the United States in 2021 assumes only one thing: the segment will continue to contract at the same rate it has over the last two calendar years. That 16-percent year-over-year annual drop experienced in 2017 and 2018 occurred after the segment began to experience measurable decline in 2015 and then a more severe 11-percent decrease in 2016. In other words, it’s entirely possible that the rate of midsize decline will – rather than slow down, as Honda hoped – pick up speed.

That would mean that a segment that was, until recently, relied upon for more than 15 percent of all auto sales could see its slice of the pie fall into the 5-percent region before the next presidential inaugural. The figures are staggering. Making the state of midsize sedan demand appear even more perilous is the degree to which virtually all members of the club were sorely affected in 2018, whether they be all-new competitors such as the Camry and Accord, soon-to-die vehicles such as the Ford Fusion, or long-in-the-tooth challengers such as the Volkswagen Passat.

In the first full year for its all-new model, the chart-topping Toyota Camry tumbled to a seven-year low.

Similarly, for the newly-arrived 10th-gen Honda Accord, sales fell to a seven-year low. 2018 represented just the third time in the last 30 years that U.S. Accord volume fell below 300,000 units. The other two instances? The recession of 2009 and the supply issues of 2011 following the Tōhoku earthquake.

Since taking over from the Maxima as Nissan’s primary family sedan, Nissan averaged 265,000 annual sales. 2018’s total fell 21-percent shy of that mark.

The Ford Fusion’s 173,600-unit total was down 43 percent from its 2014 peak.

The Chevrolet Malibu tumbled to an 11-year low.

At 105,118 sales, Hyundai Sonata volume hit a 15-year low; Sonata sales fell by more than half in just three years.

The Kia Optima’s 5.5-percent year-over-year drop wasn’t nearly as severe as the decrease experienced by most of its competitors, but the Optima still slid to its lowest level since the nameplate took off in third-gen form in 2011.

2018 was the sixth consecutive year of decline for the Volkswagen Passat, which fell by nearly two-thirds since surging in 2012.

All-wheel drive isn’t doing the Subaru Legacy any favors in this crossover-hungry age. 2018 volume fell to the lowest level since the recession.

Mazda 6 sales declined to the lowest calendar-year total in the nameplate’s history.

Headlining the group, as they always do, are the two high-volume sedans that were supposed to rescue the category. They were to be the rising tides that would lift all boats. Instead, the new-for-2018 Toyota Camry and new-for-2018 Honda Accord couldn’t even maintain an even keel.

And yet opportunity for these power players persists. The Camry and Accord didn’t decline nearly as rapidly as the segment at large in 2018, which drove their combined share of the shrinking midsize sedan segment to 42 percent last year. That’s up from 32 percent only 5 years earlier, and given the frequency with which competitors are exiting the arena, it’s a figure that may shoot past 50 percent in 2019.

[Images: Toyota, Nissan]

Timothy Cain is a contributing analyst at The Truth About Cars and Driving.ca and the founder and former editor of GoodCarBadCar.net. Follow on Twitter @timcaincars and Instagram.