1.) Leave the "no money in the future" - angle of Star Trek intact. Earth and the Federation in Star Trek is a post-scarcity society. It's one of the core characteristics of Star Trek.
No it isn't. In ~700 hours of content, it's been mentioned in a few fleeting lines of dialog.
Which means it has appeared more often than the mirror universe, tribbles, Borg and Andorians and Tellarites combined. And it was probably mentioned in as many episodes as klingons have appeared in. How can you get
more 'core identity'? The fact that you didn't
like it and chose to ignore it in the past doesn't change that. I don't like the prophets in DS9. They are still undeniable a core part of that show.
Non the less, it still doesn't change the fact that currency and economics are mutually exclusive. Nor does it change the fact that, no matter how abundant all resources are, there's always a cost, eventually.
So what? Federation economy deals in incredible large scales. Building starships and such. Processing ressources of whole solar systems. Who knows what
entire civilisations use as currency to trade with each other? Probably large quantites of non-replicatable ressources (like anti-matter or energy), or papers with options on them. In a smaller scale for human beings that's basically post-scarcity. Why would you need "money" to buy an apple if the smallest quantity of tradeable goods is "one billion terawatts", and anything below that is basically meaningless because there exists
so much of it for each individual being on the planet?
2) Don't explain how it works.
And thus the whole thing becomes preachy and unrealistic, which is why it doesn't belong.
Like warp drive? Or beaming? That isn't precisely explained how it works either. That's science fiction for you.
Again:
We have 400+ years to figure that out. If we could solve this on internet boards, we would have our Utopia by now.
My bet is, the
one true ressource in a post-scarcity society is
time. You need
time to advance in your job. You need
time to become an officer. you need
time to master a skill. You need
time to practice and become an artist. With that, society still works, people still go to work, and people still have goals in their life, because they want to achieve things that make them happy in the
time they are given. And the more
time has gone into a product - wether it's a masterfull french wine, or an archaeological find, or a painting - ,
that's what defines it's value in such a society.