Even if the law only covered non-bankrupt companies, it would already help, because most game companies don't go bankrupt (and IIRC there already are reasonably

Even if the law only covered non-bankrupt companies, it would already help, because most game companies don't go bankrupt (and IIRC there already are reasonably effective laws against intentionally planning to use bankruptcy to get out of your obligations, so creative company structure design shouldn't be as big of a problem). If you really wanted to make sure, you could require the company to deliver the corresponding assets to the national library within N days of release.