Yes, lots of books get cancelled when editors leave publishers. It happened to me. One of my novels was bought by an editor at Harcourt but when it merged with Houghton Miflin she was laid off. The book did technically get published, it was reviewed in Publishers Weekly and some copies made it to book stores but with no editor in house at the publisher it got zero marketing and publicity and didn’t sell many copies.

It is similar to what happens to movies in production when new studio execs are brought in.