might have been
/ˈmaɪt hæv ˌbɪn/
noun
- A person or thing that could have been great or successful but was not; a missed opportunity.
- The old actor was seen as a might-have-been, a star who never quite made it.
- He often wondered about the might-have-beens of his youth.
- The abandoned project was a might-have-been that could have changed the company.