Not like that would happen but if that happened they would cut costs and still go on, fire tens of thousands of people and still move on. All in all amazon is a huge company and they are doing fine and there is absolutely no reason to be sad about their loss, I rather cry about the worker they have who lives under poverty level wage.
Even if they fall into some serious problems, it is unlikely that politics will let them fail just like that, because it is still a company of great importance for the US considering that it is globally positioned. What you say about the workers is unfortunately true, because there are so many stories about it online that one wonders if it is possible for such a company to actually profit from such massive exploitation of people all over the world. But they are not the only company that operates in such a way that people are consumables that they use in the way that suits them best.