Which of the following would NOT legally terminate a listing with a broker?

The death of the salesperson would not legally terminate a listing contract with a broker because the listing agreement is between the seller and the brokerage firm, not an individual salesperson. The brokerage company continues to operate and uphold its contracts regardless of personnel changes, including the death of an individual agent. In real estate, brokers often have a team of agents, and the unexpected loss of one member does not affect the binding nature of the contracts the brokerage has in place with clients.

In contrast, the other choices involve circumstances that directly impact the contract’s enforceability. The death of the principal would typically lead to the termination of the agreement unless it is a contractual stipulation that allows it to continue after such an event. The expiration of the contract simply means that it reaches its end date, finishing the broker's obligation to perform under its terms. Voluntary cancellation by the seller indicates a mutual decision to end the relationship, which would also terminate the listing.