I can see them as O-6s, but Flag rank requires a bit more political acumen than either one has so far shown. Knowing your stuff better than anyone else will only get you so far.
O-6 has generally been one of 'those ranks', in some eras, it's the top of the Field Grade ranks, and in other eras, it's the floor of the Flag-grade ranks. A lot of that has to do with how top-heavy your command structure is, or how large your army/navy are.
Keep in mind, the
top rank in the Coast Guard is O-7, and that's equivalent in pay to a
rear admiral. to contrast this better, compare that to the LCN/LAAF-N/AFFC, where O-7 Admirals are often in command of a Jumpship with some droppers, a small surface base, or a single capital ship classed as a
corvette (the Fox class).
This is largely because of just how
vast a Great House navy really is-even if they only have a handful of compact-core ships, (or because of it) the manpower pyramid is geometrically larger. The distribution of responsibilities is slightly different with the Coasties, but proportionally they're a tiny force on the main scale of things, with a huge remit, and a lot of distributed responsibilities. The KCG's officially classed as a Lyran
reserve unit, aka equivalent to a single March Militia or RCT on the Lyran books in 3067, and by the time the 3090s came around, the organization's classed in the books as being a regional militia technically under the aegis of the Melissia Theater, and comprises four RCT's on the active duty rolls for purposes of rank distribution and equivalency.
Meaning that R. Admiral Alicia Li is the senior officer at rough parity to the senior officer of a single Royal Guards unit, but she runs a department that includes surface, space, and infantry assets as well as aerospace forces. (The glaring difference being the complete absence of Battlemechs from the Coast Guard TO&E.)
Basically, proportionally to the time/place they come from, Nicole's an O-5, Seether's an O-4. Nikki's responsibilities didn't just, at that time in her history, cover her own ship-she was a Patrol leader, in charge of a Patrol of four
Sampan-III class Cutters, plus the support tender, with a patrol zone covering a sphere roughly 5 LY in spherical radius (that's per cutter). this is because space is 3 dimensional, with added requirements out past the limit of the actual quarantine and a pursuit requirement up to 3 times her jump range.
LAAF/LCN at their HEIGHT would have an Admiral doing that job. (admittedly with bigger ships and deeper support infrastructure).
now, what this breaks down to, is that while Nikki hasn't had to do much politicking on New Circe (at least, on screen), she's got to have those political skills, because her role as both ship and Patrol commander included show-the-flag and negotiation duties.
During the war, she carried out Diplomacy that eventually got the Metis Coalition on the side of Victor and Devlin's alliance, and she negotiated the release of her subordinate (Seether) from a foreign state's 'mental health treatment' lockup, and secured minor diplomatic agreements between the Republic and the New U.S./New California (another primarily belter society). More importantly, she was able to convince Stone
not to try to force them into his new nation.Given where she is now, in the situation she's in, and the size of Clan Wolverine
and the Colonial City-state, flag rank doesn't seem that unlikely an outcome. Being allowed to take the field as a ship-commander again, however, seems VERY unlikely. Without New Circe, she and her crew are stateless nonpersons, which is what happens to you when you go back 40 some odd years and 900 or more LY from where you began-all your old contacts are either small children or ain't been born yet (except Li, who's in her
twenties.)
her role ends up being that of a
senior advisor-both because she has real-live working navy knowledge, and because she's old enough that in a Clan-influenced system like New Circe, the only naval advisory type older than she is, is Bill Adama. (and that's only by a couple years at best.)
Traditionally, going back to World War 2, and up until changes in the 1980s, Special Forces as a career ended at Colonel. After that, you weren't SF anymore, you were just another infantry officer, often with a 201 file filled with too much Black Ink for a promotion board's comfort, and a decided lack of the usual merit-badges due to said black ink, pushing promotion possibilities
downward. (this changed in the 1980s and resulted in a great many career officers going for the now-coveted 'tower of power' consisting of Airborne, Ranger, and Special Forces tabs...even when they really shouldn't have.)
Seether, no matter the service, will probably always top out at O-6, because her 201 file equivalent is filled with lots of things, but none of them for very long, and has quite a share of damnable black ink on it, which is something shared throughout the Coast Guards. with only one O-7 rank available at a time, she'll never make it to Squadron, much less Admiralty.
a little bit on that too:
Patrol Leaders are O-5's, Commander rank, Position/title "captain".
Squadron leadership is an O-6 slot, and carries the positional title "Commodore"
Between the two, are O-5(Promotable) or O-6 (Fresh) "Fleet Captains", this is usually a staff post or station command. While Nikki was an O5(Promotable), there aren't enough slots for her to hold that six. (Proportions are rigidly enforced) Further, she's good at the job. Bianh Vu Dao's intent was to wait for a Squadron command to open up, and slide Minh into it, bypassing a tour as what amounts to a glorified logistics officer in a ground post.
Technically, the Coast Guard's black water (Space) arm was a single "Division' of ships, four squadrons, of four patrols, of five ships (Four cutters and a tender each).
estimating 100 men per cutter, with a Tender's crew being roughly twice that but focused on maintenance, repair, and supply tasks.
Not including surface support it works out to 9600 or so personnel, or one understrength Regimental Combat Team by AFFC standards.
Mind you, this is eighty ships with KF drives, capital missiles, and NL-45s and a selection of combat shuttles or fighters.
But it's proportionally a smaller command than a single SLDF Battle group from the 2750s, and the throw-weight is considerably smaller.
(this also doesn't account for the non-space assets of the Coast Guard. There's a funny thing that happens when you devote 2% of the GDP for an industrialized system to defense tasks, including 2% or so of the population as part of that. Liz was a total battleaxe when it came to budgeting and she didn't let a lot of pork, favours or noble 'prerogatives' muddy the soup, and much of how the CG is organized and armed was with the decided intent of preventing the sort of foreign adventurism that eventually overtook them in the Jihad era. Most of the guys at Mt. Asgard didn't see a force without 'mechs as viable assets for deployment to the usual meatgrinders, esp. when the bulk of it is focused on Maritime activities and/or esoteric shit that isn't applicable to the current paradigm.)
What the Wolverines have gained, is someone who knows how to run a
working Navy, something that is kind of a massive force-multiplier all on its own when combined with the mothball ships they already have. this also highlights their glaring lack of personnel, but Seether and Nicole got their start in a tiny service (relative to contemporaries) that was tightly funded and had high standards.
There are historical parallels to this; European advisors to the nascent Continental Army and Navy during the Revolution (and after), the Prussian influence on the U.S. military from that era can't be underappreciated-while armies raised under Spanish, French, etc. doctrines all grabbed for the brass ring (overthrowing their governments and installing various military juntas), the 18th century Prussian influenced U.S. military never countenanced a coup against their civilian leaders. This is likely one of the largest reasons that the Western Hemisphere's most powerful nation isn't in the wealthier southern landmass-Professionalism breeds stability, Stability breeds prosperity. You can't have a prosperous nation if the army is wrestling the government for control.