Offer your thoughts or opinion on the input financial query or topic using your financial background.

What happens to your spouse's sole proprietorship if they die?
For sure you should get a lawyer on this one, but it would seem to me that the simplest path forward would be to convert the business to a partnership where both spouses are owners, and to write a clause into the partnership agreement stipulating what happens upon death of a partner.  Such an approach really should be done with a lawyer to make sure that it's all legally sound and will stand up in court if needed.