That's a great take on "Merrily", but I think it only really works if you listen to a few of the songs and ignore the actual book of the show and the characters as written - which people have tried to do for 40 years without cracking the code.
Your take also presumes that the kind of things young 20 year olds say - "we're brilliant, unique, and going to change the world!" - have any real weight. My biggest disappointment in finally seeing Merrily was discovering that it *wasn't* the story you describe, and which I expected, because none of the characters rise to that level of greatness for even a moment - but that greatness is generally an illusion (or delusion) of youth to begin with.
Instead, we have three people with high hopes who discover that in the act of living and making choices, they disappoint themselves and each other.
And most of all, your version of the story is told forwards, but the show is told backwards. And that backwards telling really mucks things up without having a strong enough pay-off. The show only seems to work as an album, where we can dig into the arcana of the songs once we already know the story - or have the freedom to fill in the blanks and tell our own.