I think it's clear. Nobody likes the idea of putting the Rommies with the existing factions. NOBODY! NOOOOOBOOOODYYYYYYY!!!!!
So what's a somewhat REALISTIC way to put in a 3rd faction?
(Don't talk about species!)
1) The new faction has less levels. Whether you go from Cadet to Captain in one feel swoop like JJ-Kirk (and basically have Tier 1 then 4 and 5, no tween ones or something) or just start at Commander and go up doesn't matter (tier 4 and 5 or something). There's less levels. Perhaps 20.
Why you ask? It's much more realistic to make content for a limited amount of levels and ranks when there aren't as many.
You can make a third faction with depth, unique missions and really good. Just smaller. More compact. Easier to make. Just as meaningful and fun.
So basically the 3rd faction should have 20 or so levels. Enough real PvE missions to fill that content (maybe including Episodes). Tiers spread out or linear. The only reason I say they might be spread out is if you have a Cardassian or Romulan faction I don't want to see the Hideki or TOS BoP (C-Sore ) higher than Tier 1. And you can't have tier 1 in 20 levels if you don't skip up at some point. And I DO want those ships palyable. Just not at higher tiers. So maybe the faction might jump up like 30-40 levels at some point.
2) Because you level quicker (due to there not being as many levels) you'd ONLY be able to make a character of this faction if...
A) You pay into the C-Store (maybe)
B) You have a max level Fed or Kling character (or perhaps just one ranked up to a certain rank like Captain or Commander)
Quicker leveling would be unfair otherwise.
3) As long as there was enough PvE content for those 20 or 30 levels and enough ships and end game stuff (the same amount as the other factions) and a good story I think this would be the way to go with a 3rd faction.
So in short... Upon reaching a certain rank as a Klingon or Federation character you'd access the third faction.
This faction would have less levels but by the end would be at the same level and have the same access to end game.
Due to less levels it would be easier and more realistic to make content for it.
The faction would basically be a full faction as far as end game is concerned. And a few less levels wouldn't kill anyone.
i cant see why they cant be added like klingon the only main instance i can see a problem is that due to lack of open pvp zones that how do you balance pvp encounters if there is 1 rom 3 fed and 2 kling, so i think they should implement a free for all zone or dont bother.
i think unless romulan is its own faction its not going to work.
I've been a proponent of an abbreviated level track for the next STO factions for awhile. I'm not a huge fan of the level 6 and unlock KDF, but it was my reality even if they change this in the future, but I do not believe that there are enough canon ships, ranks and material for a full 1-51 level progression for any remaining faction. If there was not enough for the Klingons, Gorn, Orion and Nausicaans there is not enough for the Romulans or Cardassians, even if you add in Hirogen and Jem'Hadar.
This is the list of basic essentials I made for the Romulans
My basic list
A Romulan faction that feels Romulan even if aligned with other factions. Not like the Gorn et alia in the KDF, but a separate entity.
Gameplay that reflects Romulan sensibilies. The Feds have their Diplomatic Corps, the Klingons need a house system and the Romulans should have something their own, something rooted in deception.
A backstory/storyline that acknowledges the deep rooted animosity between the Romulans and Klingons, as well as the cat and mouse nature of their relationship with the Federation.
A level progression that reflects both the current situation "in universe" as well as the rich Trek history of the Romulans. It does not need to be 1-51+ but whatever the levels it should capture the Romulan essence.
For me this list essentially applies to all future factions, inserting the proper canon concepts where applicable. I think it is more realistic to see a list like this met if they don't have to worry about 51+ levels worth of content.
There's plenty of variety of ships and weapons for Romulans, Cardassians, and even Ferengi to have their own factions. Might be pushing it beyond them though.
There are fewer canon Romulans ship classes (Romulan BoP: 2 types, D'deridex, D7 which they got from the KDF, Romulan Science ship, Romulan Scout ship, Valdore type, and Scimitar) than there are canon Klingon ship classes (BoP: K'vort, B'rel and D12, D5, D7, K't'inga, Negh'Var there are at least three variants of this ship, Raptor, Vor'Cha) and yet they had trouble filling out a full 5 tiers of ships for the KDF. The Cardassians have 3 canon warship types the Hideki, Keldon and Galor plus a handful of transport/freighter ships.
Parallax beat me to it while I was adding links :p
Of course this also doesn't account for the complete and total dearth of canon material for Cardassian ranks... Glin, Gul and Legate. The Romulans have more than that, but they are as bad a mess in sorting out as the Klingon ranks are and I've never been thrilled with how those got sorted out.