Well it's two situations. Look at Google dropping the older Nests. There you can lay in a fine.

For the folding company could make it part of declaring bankruptcy. Standard paperwork.

Either release all your source or prep the needful. Once this is common and expected could even force companies to maintain a public branch to release on cue.

Owning IP is fine. Products ending up in a landfill due to software is not.

Hopefully the law also expands to actually owning all of a product you own. Not paying BMW to unlock the heated seats already in the car you fully paid for.