There are several kinds of "sedan style cars" that Americans have been buying in the last decade or so.
1. The hatch, also sometimes known as a "hot hatch" because it might have some jazzy performance.
2. The highly bespoke luxo-sport sedan.
3. Toyota Camry, Nissan Altima, Honda Accord.
Although American carmakers, particularly GM, have indeed made cars similar to the Camry, Altima and Accord with what could be argued EQUAL and sometimes better quality in the last decade or so, the fact is, Camry, Altima and Accord owners WILL NEVER EVER EVER EVER switch.
And, the Camry, Altima and Accord were STILL just a teensy weensy bit better anyway.
The US manufacturers lost that market segment for the most during the 80's when they started making absolute crap and they never were able to win back that market to the point where it was super profitable again, despite making a decent product once again. And an entire generation grew up SINCE then, conditioned to accept that when one looks for a sedan, one looks to Toyota, Nissan or Honda.
The only way GM, Ford or even Chrysler were ever going to find enough profitability in that market was going to be if they stomped Toyota, Nissan and Honda into the ground and claimed the Numero Uno spot.
They should be happy that they got #2 or #3, and I guarantee you a lot of people are impressed, but it wasn't enough given the overhead here in the U.S.
The US has never made a decent hot hatch except for the Ford Focus, and most of the market for those is EU anyway.
And the luxo-sport sedan market belongs to Mercedes, and BMW, and always has.
Nowadays it could be argued that we make a very GOOD luxo-sport sedan, like the Chrysler 300, but it's not THE BEST.
And again, with our overhead being what it is, if we aren't going to be #1 by a wide margin (stomping a mudhole in MBZ-BMW) we cannot make enough profit to be sustainable.
Ford finally figured it out a while back. Ford will continue to offer Lincolns, and the Mustang.
That's IT for Ford in the car market, PERIOD.
GM is now finally admitting the same. They realize that they can probably offer ONE Buick model, maybe TWO Caddy models, and the Camaro and Corvette and that's all she wrote.
And FCA (formerly Chrysler) might just kill the series that replaces the 300 pretty soon, I would wager twenty bucks on it.
The fact is, if Americans buy American vehicles, they mostly buy crossovers, minivans, small SUV's, large SUV's and pickup trucks.
And as far as killing the Volt, they are killing the Volt because it is ALSO a SEDAN, despite the fact that it has a hatchback.
It is STILL a four door sedan and Americans do not buy very many American four door sedans.
Voltec hybrid technology is probably going to live on, at least for the next five or even ten years, just not in a four door sedan.
And GM is stating that it really intends to transition, as soon as possible, to FULL Battery Electric Vehicles anyway, so Voltec technology style powertrains may eventually give way to full EV powertrains anyway.
I expect we will see Volt powered crossovers and small SUV's for a few years more, but only for as long as it takes for the electric charging infrastructure to become accepted as ubiquitous and thoroughly commonplace throughout the entire country.=, and for the battery technology to transition to the point where ten or fifteen minutes is more than adequate for sufficient charge time to keep a vehicle topped up enough to travel within humanly feasible range for a full day's driving.
The core mark for that is 65% charge. If you can top up a BEV to 65% charge in 15 minutes, and the vehicle has a max EV range of 250 miles, that puts it within the acceptable outer range of human driving capability for a day's drive, because 250 miles on a full charge plus another 175 miles equals 425 miles, and that equals about seven hours worth of driving.
Add another fifteen minute top off and you get 600 miles and that's eight and a half hours worth of driving.
The majority of people seldom drive for more than eight and a half hours in a day. That's not to say there aren't road dogs like myself who can do twelve hours without flinching, but people like me are the exception, not the rule.
So my point in all of this is, car mfr's see that as a golden meatball, and GM sees it as something doable by 2022 or even sooner.