By the story and the writers/creators. Her humanity is slowly being eroded. So, what will she become?
A vampire is out. That would undermine the very purpose of the show. So it has to be something else. She is a variation of some kind, possibly a werewolf or similar.
http://midnightfire.blogspot.com
her humanity seems as intact as it has been since she first woke up in ep.1 IMO. i don't think she's becoming someone/something else. even after Susan's death she seemed like the same Vanessa (to Mohammad) that she's been from the get go...but one never knows with this show so you may be right as well. :)
shareJust in case : SPOILERS for episode 11.
If a character in this show is keeping his humanity, it's definitively Vanessa (so far). Episode 11 is a good proof of that. For a character supposed to "lose her *beep* pretty easily, I expected Vanessa to go ballistic against Sam and to chop his head off out of rage, but she didn't. Out of sympathy, she didn't even want to off Sam in front of Mohamad. She remained strangely collected.
In episode 11, Rebecca referred to Vanessa as creature with "vampiric qualities", saying that she is "more like us [vampires] than human". Considering how little was revealed so far about the Vampires, I'd rather focus on them than to have other creatures introduced in the show.