The primary reason I make this assumption is because Arthas, Rise of the Lich King states that Arthas raised her rangers from life as Banshees to throw her a bone as additional torment to her undeath.
There are certainly Banshees that remain in ethereal form within the Forsaken ranks such as Melisara in Tarren Mill and Sharlindra adjacent Sylvanas.
My primary question is this. Have other Banshees exhumed their own corpses to follow Sylvanas as their ranger-general in death, or are the existing Dark Rangers simply elven forsaken or are the Dark Rangers a cohesion thereof?
To expand upon this are the Dark Rangers just now exhuming their corpses or have they been in hiding or away on secret missions out of the player's sight for years? Sylvanas' corpse was kept in a coffin by Arthas as additional torment for her but it is hard for me to believe that he had a coffin for each individual Banshee as that would require a lot of resources and management for something so unimportant to their cause. I do not think it would be a stretch to say that the ranger's bodies could be mostly preserved due to Quel'dorei magical longevity and the forces that maintain the eternal spring of Quel'Thalas.
Where are the male Dark Rangers? Nathanos Blightcaller would be the exception to pretty much every rule in the above as Banshees never seem to be men. This was suggested with the title of the Acherus exclusive; Touch of the Banshee (http://www.wowpedia.org/Touch_of_the_Banshee). Certainly not all of the rangers under Sylvanas' command were women as her replacement, Halduron Brightwing, is male himself.
If Dark Rangers posses limited powers of necromancy or sorcery as they seem to exhibit, where the average Forsaken does not, and the source of this is their origin as Banshees then why does Nathanos Blightcaller Marris possess command over the undead, as seen in the vanilla wow raids on his character?
If a Dark Ranger posses her own body, are there consequences? It would seem to me that a Banshee possessing her own corpse would be no different than possessing any other. Yet when Lord Vincent Godfrey turns on Sylvanas and kills her at the end of the Silverpine Forest Horde chain she does not appear to escape her body and become Banshee once again. Does this mean that there are special rules regarding Banshees and possession? Ones that could perhaps refuse their spirit to the corpse for good trading Banshee powers for corporeal undeath permanently?