What would happen if the site's domain changes? Or my email changes? Or something else about the metadata changes? Now what if this happens on a site where you

What would happen if the site's domain changes? Or my email changes? Or something else about the metadata changes? Now what if this happens on a site where you can not reset passwords, such as blockchain.info, am I SOL? I like storing passwords becuase I have 100% certainty that it won't just magically generate the wrong one.