Now, a fancy pictograph-thang. Yay. Below I give my explanation for the hierarchy and address what I think will be common questions.
What is the High Council?
The High Council, or "War Council" as it is also being called (I chose High Council because I think it's a better name) functions basically like a combination of the Dark Council from the SWTOR era and the Moff High Council of the Krayt Empire era. It's pretty much the same War Council idea that is being tossed around, containing all of the faction's most powerful Sith, with the addition of its most powerful NFUs. The High Council convenes to make virtually all of the Empire's major decisions, from government policy to war, and is second only to the Emperor/Dark Lord himself.
But wait, why are there only 3 Voices?
We have always had 5 Voices, but historically these positions have been very hard to fill. It has been quite difficult to fill all five of these positions at the same time, something we've rarely, if ever, accomplished. Currently, we only have 3 active Voices, which seems to be the norm. So I've pared the position down to only 3 Voices, to include the ones we have right now. And, as per the job description, the galaxy would be divided into three, rather than five, spheres of influence.
This also opens up more room for NFU-exclusive positions on the High Council, which is what some people wanted to see. You'll notice that there are now not one, but two High Moffs, who sit on the High Council. I've also included the Director of Intelligence on the High Council (yes, in case you forgot, we have an Intelligence sector), based upon the fact that this position was also very prestigious in the Krayt Empire era, and it provides another avenue for NFU characters to attain power.
I'm reticent to add any more positions to the High Council - we're already at 11. Theoretically the High Council would best operate if all these positions were filled by active characters. If we have too many positions and not enough characters to fill them, that's going to be a waste.
Why aren't Grand Admirals/Grand Generals, etc. on the High Council?
Simply because Grand Admiral and Grand General are no longer the highest possible positions a NFU can obtain. They are now superseded by Moffs, the High Moffs and the Director of Intelligence. This, again, is based slightly on the Krayt Empire where Moffs generally seemed to wield more power than Grand Admirals and Grand Generals.
However, Grand General and Grand Admiral positions are still powerful, relatively speaking. As you can see, they would be equal in rank to an average Sith Master, as they fall under the "high ranking military" tier, and as such would still command a good deal of authority.
Do NFU's have equal opportunity for progression of power as FUs under this system?
This seems to be a common concern, and the answer is yes - in my opinion the system is quite generous to them, perhaps overly so. Observe that Moffs are actually more powerful than most Sith Masters. The only Sith they have to answer to are the ones on the High Council. That makes them quite powerful. And the High Moffs and Director of Intelligence are of equal rank to literally the most powerful Sith.
In my opinion, this gets rid of the need to open the Voice position to NFUs. They now have their own unique avenues to power and don't need to converge on the Sith titles.
Aren't there too many positions for Elite/Master rank characters, and doesn't that make the system a little top-heavy?
You'll notice that I color-coded the chart to show how the hierarchy fits into our rank system of Apprentice/Trainee - Knight/Adept - Master/Elite. Yes, there are a variety of unique positions open to only Master and Elite rank characters, much more than those of lower ranks. However, this is something that is actually desirable.
What this means is that your character's progression does not end upon hitting Elite/Master rank. In fact, that is only the beginning of an entirely new avenue of possibilities. Think of it like the endgame content of SWTOR. For those of you who have played, you know that hitting level 60 isn't the end of your journey, but in fact when the real game begins. It's the same idea here.