Sean McCarthy, founder and sole agent for Sean McCarthy Literary Agency, discussed what makes a work viable.

He gave four requirements.

  1. It has an arresting commercial hook.
  2. It has an internal or emotional core.
  3. Character transformation takes place.
  4. It has a fresh, original concept.

Related to that, I believe, was his comment on issue-driven versus character-driven projects/books.

Issue-driven books are published by educational publishers.

Character-driven books are published by other publishers.