@FairWeatheredFriendDon't remember ever coming across a plotline such as this before, but would be very interested in reading such a story. I can envision many different ways the story could be built around that type of plot and many, many different scenarios that could be developed from them.
Intro example:
Greetings youngling! I am XXXXXX a god of XXXXXX religion. The current pantheon of gods is considering retirement and looking for potential replacements among mortals. You have been selected as a candidate if you choose to accept the honor.
Upon acceptance, you will be endowed with abilities and admitted into a special university where you will learn to develop those abilities and compete with your fellow candidates to grow stronger. The current gods, and all previous pantheons as well, will be your mentors, instructors, and examiners. All candidates will be constantly evaluated throughout the schooling to determine the best selections for our replacements.
If you choose not to accept this honor, or for some reason you are dismissed from the training, you will be returned to your previous life with no memory of this invitation or the schooling.
If, however, you accept this honor, successfully complete the training, and impress the gods enough, then you may be invited to be part of the new pantheon that is going to be formed.
Make your decision!