The only Chaos faction is CSM... so no, no marines female.

CSM often use heretics on the field of battle. Heretics aren't limited to male. Psykers are mostly not marines.
As a hero class they are possible.

The faction is CSM, no CSM + cultist... Cultist will be the counterpart for the imperial guard i know in tabletop cultist form part of the CSM army, but this is not tabletop and we already saw no cultists on the pre alpha footage and the devs never mentioned anything about them.

The devs mentioned possible hero classes and possible psykers. We have already seen psykers from Space marine - the game that is heavily influencing Eternal Crusade so why are you so against this ?
Also making me look for sources on this. Geeze man:
from this thread: http://forum.eternalcrusade.com/threads/compilation-of-info-about-eternal-crusade.1959/
Psychic powers will be available and players should be careful to avoid the perils of the Warp when using them (Source 1, Source 2, Source 3)

They would more likely have chaos space marine sorcerers if they don't have any cultists in the game

Exactly, Psyker only means having psychic powers, and CSM have Sorcerers for that, SM have Librarians, that's all it means IMO, not the actual unit called Psyker.

And no one is against there being Cultists in the game, but just like IG, they just won't be in the game at launch. Though personally, I'd be terrified being a cultist in a battlefield filled with space marines, eldar and orks =P.

Both sorcerers and librarians are incredibly rare that's why I'm assuming they would use psyker enemies similar to those in space marine.(opinion)
But back to the topic at hand. If this idea is discarded then there is nothing for CSM since no demons will be in at launch. For sm a small possibility of a really rare inqisitor hero class that needs a lot of things done to be unlocked. Any other ideas ?

I think as things go, it may be the Eldar with the Gender selection. We see male and female in their army listing. Like the Farseer, Banshees and so on.

Uh, they're not rare?

Most of the Ultramarine Descendents keep strong Librarius Contingents, most of the first founding sub chapters do.

For Chaos there are actually a LOT of CSM Sorcerers.

This making me think that Behavior might go with a Multi-gender faction with their next faction update whenever that might be. I would assume Tau, however I don't know how they'd add IG or Sisters of Battle considering that are completely seperate entities from space marines, but they fight for the same faction. So I was thinking they might extend spacemarines in the future to "The Imperium" as their faction and extend the classes via that.

^All Speculation