If you think Amazon will refund you 3000 dollars worth of digital goods in 50 years if they go bankrupt, you're dreaming. If you're very lucky, whoever bought them out might let you keep your stuff, or more likely, let you buy it again.
In 50 years their code will be cracked or the root keys leaked (especially during a bankruptcy meltdown). Of course that’s not something to count on, but history is a proven record that opsec failures will produce the opportunities for “liberation”
No need to wait 50 years if you wish to break the law. Right now you can steal all the content you like. Don't forget removing DRM in the US is illegal, and laws will undoubtedly only get more draconian.
Many of them trade this for convenience and assume there will be an off-boarding process.