This may be a bit misleading when you say "car". Trucks, SUVs, the Mustang, and Focus are still going to be sold. I was thinking when I first saw this that only two platforms were to be sold in the US.
I understand their reasoning. The market is just not strong enough for coupes/sedans. Everybody likes "big" and the trucks/SUVs/CUVs check off the box for most. Change is inevitable but I would REALLY like to see more consumers buy sedans/hatchbacks/shooting brakes/wagons. Does this mean consumers don't really care about MPGs? Actually, yes. From experience in cost savings and consumer needs, people who buy the bigger vehicles don't care for gas mileage.
Go to Europe, they sell Skoda, Seat, Citroen, etc. These all have small petty turbocharged motors that wouldn't last in America's economy for two reasons: size and branding. Also, it wouldn't help with a small car like that barreling down the highway at 80 mph in 6th gear @ 4k rpm. The country is simply too big for these cars. Europe makes much more sense. According to carsalesbase.com, SUV sales in Europe alone have actually increased by 30% in 2017. The shift to these vehicles will continue for awhile.