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The Roadster was a rushed production job. The cost of warranty repairs to smart is often noted as the cause of smart killing it. And these aren't little issues either, these are "turbo died" or "water leaks onto computer unit" bad.
The diesel died with the 451. We're also half the size of a Prius, so nowhere to store a hybrid drivetrain.
In my opinion, you're really only pointing to factors in smart's demise in the US, but there is far more to this story.
The US is very different from Europe. City cars are less practical here, there is no government incentive to driving a small car, and small cars only sell well when fuel prices are high.
In fact, cars are selling so poorly in this country right now that major manufacturers are phasing out their cars and building only trucks, SUVs, crossovers, and muscle cars. If sedans can't even sell enough to make the cut, a smart would never stand a chance.
Clearly, even smart knew the odds were stacked against the fortwo because they planned to enter the US market in 2006 with a SUV instead of the fortwo.
They could have imported the diesel here and I'm sure that would have sold well at first, provided the price was right. However, we now live in a post-Dieselgate world where automakers are now shying away from Diesel in favour of electric.
Long story short, smart would be doomed in this country no matter what unless they offered a larger vehicle. The forfour would be a great start, but it would have to have a competitive price.
As for the overall brand (as in, not just its health in the USA), these cars actually sell well and are quite popular. The smartville factory ran at capacity for a number of years.
It appears the problem is that Mercedes-Benz burns far more money than they would make back. All these suggestions like opening new factories and such are pointless if MB can't get their spending under control. If I recall correctly, MB was losing something like $8k for every smart sold up to 2008...and it's not like these cars were super cheap back then, either. Teaming up with Renault and building a car that squashed complaints of previous generations seemed to be their plan for saving smart, and it appears they somehow managed to mess that up, too.
But that's all in the past now. Geely has laid out their plans for saving smart and they are solid. They will build a car in the B-Segment (larger than a forfour) and it'll be all electric. Since China loves smart and China loves EVs, I expect them to sell hilariously well. The larger size will also accommodate better EV tech, which means they will stand a better chance in an America where EVs are more popular than ever.
