Bankruptcy sells the assets on behalf of creditors that have specific priority in law. Just releasing code to users would be a pretty serious abrogation of creditor rights.

The most likely outcome is that some PE firm would buy the software rights out of bankruptcy and figure out how to bleed money out of people that want to continue using that software.

Besides bankruptcy there is also shutting a business down, in which case are no new owners. Lavabit and Silent Circle being examples of businesses that shutdown rather than comply with laws they didn't like.