I don't like the idea of flipping the meanings of "you" and "thee." I think it is possible to convey in the show the accurate meanings of the pronouns. In many cases, the context should help the viewers determine the difference between them, as it will be clear whether a scene depicts a formal or informal conversation.A comment on thee/thou/thy vs you/ye
I do think that is an easy way to make text appear archaic to a modern audience, while at the same time adding a layer of depth to the dialogue by differentiating between formal and informal speech. It is likely no mistake at all that the Valar are consistently familiar in their address of others (unless addressing an entire group of elves or something). And likewise it relays some of the tension in the story to have the Melian/Galadriel and Angrod/Finrod/Thingol conversations use 'you' - they may be relatives, but no one is losing sight of the fact that these Noldor are 'foreign guests' in this kingdom, and Melian and Thingol are Queen and King. There is a distance/coldness/formality to these interactions that show they are at odds with one another.
Of course, it's unfortunate that the "thee/thou" dialogue will sound more formal, while the "you" dialogue will sound more familiar to the audience.
It is my understanding that in French, one reaches a point in a relationship with another person where you actually discuss whether you may now call the person by "tous" (informal) rather than "vous" (formal). Ie, that there is a verb for 'calling someone by informal tous' that is used when transitioning from acquaintances to friends or what have you. We may have to have a conversation like that on screen at some point - for instance, the first time Celeborn/Galadriel use "thee/thou" with one another or something may be the time to highlight that this is the intimate/friendly version of you, not the King James Bible (or whatever other associations the audience may have) version.
And obviously we can have Fëanor refuse to ever use thee/thou with Indis (except perhaps for when they nearly reconcile at his wedding to Nerdanel).
Certainly, we can have people address their subordinates as thee/thou, while the subordinates always carefully respond with the more formal "you."
But I do think that this distinction between you/your and thee/thou/thy is one that will carry through all seasons of the project and most of the cultures we present. Except for hobbits, of course.
Another option is to flip the meaning - to have 'you' be informal/familiar and 'thee/thou' be formal/distant. Obviously that's not how it was used historically, nor does that mirror what Tolkien did throughout his stories....but it may be a way to 'cheat' and get the audience to have the reaction we want them to have when they hear the distinction between the voices. Because the reality is that the archaic version that has fallen out of use is going to sound remote/distant no matter how we prime the audience to understand the distinction. It's more-or-less what Tolkien did with Pippin and Denethor. I think we should consider that option, at least.
I like the idea of a conversation explicitly mentioning the pronouns people are using with each other. Perhaps we could aim to have one of those in the first few episodes of each season. Another thing we could do is, in Season 1, have young Estel giggle at the archaic language Elrond is using when telling him stories and have Elrond give him (and the viewers) a brief grammar lesson.
Also, I think that understanding the difference between "you" and "thee" is not absolutely necessary to enjoy the show. A casual viewer may just hear those words and think they sound kind of cool and old-timey, while a more engaged viewer would pick up on the difference between them and the extra layer of meaning they add to conversations.
"Ye" is the second-person plural and, in modern English, has been replaced with phrases like "you guys" or "y'all." I think this is something that will also be quite clear in context, as characters will use it when referring to multiple people.