that's a cover from "x-men: the end," and has nothing to do with normal continuity. therefore, this "phoenix, but not in jean's body" thing is just unnecessary speculation.
in the "the end" stories, jean manifests the phoenix raptor and all the accoutrements, and possesses the power of the phoenix. how that exactly ties into the nature of their relationship, i don't know, but it's utterly unimportant to this topic. the person in the phoenix costume is jean.
the redhead on the ground is most likely madelyne pryor. speculation started way back that "dust" was really madelyne, and that the dust v. madelyne fight did not end as the panels suggested. (it looked like dust stripped madelyne's body down to the bones.) there have been hints dropped that the dust seen after that fight is really just madelyne in sooraya's robes. these hints include a close-up of dust's twinkling green eyes, which are very reminiscent of madelyne's and jean's. also, she comments that emma isn't the only one who knows how to take care of [scott].
my guess is that in the latest issue, dust is revealed as madelyne, and this cover has her protecting/comforting/whatevering scott while jean manifests the powers of the phoenix in the background. how that ties to the story, i have no idea, because i haven't been following it. it was a sucky read, pretty much.
the image does look edited, though, like someone took a picture of jean as the phoenix, and dropped a cropped picture of scott and maddie on top of it.
Gender: Unspecified Location: IN YOUR MIND...MUWHAHAHAHAHAHAHA
If you look closely the woman is not a red head she is blond, the phoenix effect is illuminating the pic giving everything a reddish-orange tint, so i say it's Emma.
where's the evidence of her hair color? the "phoenix effect" isn't turning anything else particularly red, as seen on scott's face, hair, the x on his chest. it's really only causing mild redness on parts of the woman's face, which, being white, should be as equally red-receptive as blond hair. but her entire head is red. not just a little bit of it.
and that doesn't look like emma's hair, clothing, or even her face at all.
That look sway more like Maddie then Emma, (Emma would never wear black) and that is clearly the same kindah outfit that Maddie was wearing before she battled Dust.