If it counts as complete retraction, the first person receives nothing, whether the sick person dies or recovers, and the second person receives his share: if the sick person recovers, as a gift, and if he dies, as an inheritance.
However, if it is a partial retraction, then if the sick person dies, the two receive their shares, but if he recovers, both receive nothing - as in the case of a sick person who leaves something over.
The law follows the first possibility.
Art: The Sick Doctor by Jehan Georges Vibert