If AWS goes down unexpectedly and never comes back up it's much more likely that we're in the middle of some enormous global conflict where day to day survival takes priority over making your app work than AWS just deciding to abandon their cloud business on a whim.
Can also be much easier than that. Say you live in Mexico, hosting servers with AWS in the US because you have US customers. But suddenly the government decides to place sanctions on Mexico, and US entities are no longer allowed to do business with Mexicans, so all Mexican AWS accounts get shut down.
For you as a Mexican the end results is the same, AWS went away, and considering there already is a list of countries that cannot use AWS, GitHub and a bunch of other "essential" services, it's not hard to imagine that that list might grow in the future.
what's most realistic is something like a major scandal at AWS. The FBI seizes control and no bytes come in our out until the investigation is complete. A multi-year total outage effectively.
Or Bezos selling his soul to the Orange Devil and kicking you off when the Conman-in-chief puts the squeeze on some other aspect of Bezos' business empire
