What 9x03 taught me is that the erasure is somewhat less, if not unimportant, of a worry than rape, in this show. Because a female character can be used to simultaneously rape and heteronormalize a queer-leaning character, but only one of those can exist at once, so you get half of fandom thinking it's erasure and the other half recognizing it as rape. We all freaked out over 9x03, scared the same way as we are over Dean and Ann Marie, for many reasons (and P.S. I remember very clearly that half of fandom thought Destiel shippers sent hate to that actress, and she said it hadn't happened, so people are jumping the gun here; P.S.S. You know what dehumanizes female characters with the added bonus of doing very little to help anxious rape and abuse survivors? When you tag them "Dean x other" or "Cas x other" instead of "Dean x Ann Marie" and "Cas x Meg/Cas x April/Cas x Daphne etc.").
I was worried the most about allosexist treatment of Castiel, and my worries were shown to be justified, by canon and fandom, when people took that rape and ran with it, shitting all over the sexuality Castiel has exhibited up till now by saying "now he's human, he's sexual" and refusing to think for a second about the consent issues in the rush to make Castiel allo like them, much less warn when discussing it in view of survivors and ace people.
That act was rape (By Deception, survival sex, intent to harm, coercion, impersonation of a trustworthy party; you name it), and allo people are still defending it (in the same manner as they are 6x10's sexual assault via forced kiss: as a sexual awakening by surprise sex act Castiel "enjoyed"). I never saw a post apart from those of ace spectrum people discussing the complicated issues of sexuality surrounding it, and I could not have been less pleased with fandom for how it was dealt with.
But the writers didn't know that when they wrote it. And fandom, in large part, didn't either. Everyone, PTB and writers, needed to be worried about that, and they weren't.
So here we are at S10 and we're back in Reaper!April territory, and fandom is again worrying overly much more about one than the other. My worries are not that the "intense fling" that'll show Dean "has some devil in him" will have anything to do with long-term romance or act as no homo/bi to destroy the Destiel structure. My worries are based entirely on a far more pressing issue: that "intense" will mean rape from a "devil" Dean. I don't want another Meg, or Ruby (which, if someone has a GIFset of the 4x09 Ruby/Sam scene in full, I'd appreciate it being sent my way, because the more I watch it, the more ways I'm certain it's rape--as much as Meg and Cas would've been as he repeatedly made clear he wouldn't consent, dead meatsuit or not, and I'd like to make a post of just how.) or Lilith, or Abaddon, or Crowley, or Azazel, or Alastair. I don't want another rapist, and I certainly don't want that rapist to be Dean, whom I'm expected to sympathize with. If they show his guilt and regret, I may be able to come back from that (as they never do that with demons in SPN, Ruby included, and it would show well his dueling natures; unlike with Spike, it won't have come after two seasons of abuse and Nice Guy esque predatory response of the person he then assaults), but regardless, it will be a huge blow to me as a Dean fan and a rape survivor.
My worries are based upon the fact that demons don't have sex--don't have flings, they rape; demons sexually harass, demons sexually assault, demons pointedly sexualize their violence, their words, and their coercion and manipulation. Demons and sexual acts = rape. This is indisputable. Every demon who's recurred, as far as I remember, at least, has shown themselves to be sexually predatory, sexually abusive, or outright rapists. My worries revolve around the fact that the writers are so unaware of the consent issues surrounding demons that this is one of the first spoilers we get, as though a demon in an act construed as sexual is an enticement, which goes to show, as we know by 9x03, that the writers/PTB who are going to write this have no self-consciousness about how they are portraying anything related to "sex", including in in regards to demons. Possession is one thing, and one we won't have to worry about with Dean, because his body is his own, but demons rape in more ways than that.
Love interest is deeply unlikely, fandom, you're missing the point here with your anxiety (and though I empathize with the fear of erasure, S9 was more consent issues than erasure, if you paid attention). Rape, however, is likely, so maybe worry about that instead. I'm sick with anxiety over it.