I don’t think there’s a chance in hell this is going to be the next Anyone Can Whistle, Love Life, Merrily We Roll Along, or Chess, that people are lamenting what went wrong and still trying to make work 30 or 40 years from now.
But surely that's exactly what Flying Over Sunset already is. None of those shows you named is any lost masterpiece. They're all examples of shows that don't work, and are very probably never going to work--certainly not in the commercial-Broadway sense--but that a lot of people happen to like anyway. Like Flying Over Sunset.