I have a suggestion. I was reading over the plans for season 7 and heard a pod cast about mini Factions. It was mentioned about the Romulans where you hears a story line and you get to a point where you decide to help Klingons or Feds but they have there own uniqueness.
Anyways I am just watching Star Trek Voyagers Unimatrix Zero and I though hey that is a faction in the Collective that could be a mini faction. If the borg ever become a playable species with there own story line could we have it as Unimatrix one.
The story line did not carry on and as the episode went on it sort of left it as a cliff hanger where they revolt on a few vessels but we never knew what happened afterwards.
That is one suggestion.
The second suggestion is to have a Unimatrix Zero Featured Episode that outlines what happened to Unimatrix one after they revolt. From the story line from Voyager it indicated that they took over a few vessels but it did not out line what happen of weather the Borg Queen won or did unimatrix one still to function etc.
These are my 2 suggestions. I hope someone will put it on the suggestion list as maybe a borg subfaction as obviously you cant make the borg a playable faction directly as the are a major antagonist but you can always use a splinter faction that rebells from the main group. They may not be as super powerful as the main borg faction but can have a faction that is equally balance but might bring a few borg goodies with it.
I would even be just happy with a Feature episode as it is a story that is still untold.