See here is the thing: I heard on the interview, the storyboard artists said Misty will probably not be coming back.
See, here's the thing. One of the reasons why we should take that interview with a grain of salt is because Masamitsu Hidaka (whom, while he did used to be Director of the Series, is now, in bold, a storyboard artist.) isn't in a position of power to determine these things in the show. What he says isn't written in stone, especially considering the fact that after season 9, he was demoted to nothing more than a storyboard artist.
Of course, I probably wouldn't believe him even IF he was still the Director (which, other than being a writer, is the closest to having something written in stone as one can get.), considering how he lied about us meeting Ash's father in Season 5, had legitimately, absolutely no idea that Platinum was coming out despite it being a common-known fact that even Corocoro not only knows about, but constantly talked about it's progress, and that two forms in a certain recently released movie about Shaymin debuted in Platinum, even though in that same interview, he bragged about how Ash was going to stay in the series for as many game generations as the games can produce, as well as he himself admitting that he was thinking about permanently removing Brock from the franchise during the OI, but changed his mind, but that's another topic, anyways.
speaking of topics... On topic: It seems to be a likely outcome. I think that the only thing that MIGHT throw a wrench into it is the fact that Cynthia owns a Togekiss as of now, but then again, considering how they aren't bothering to use Platinum's lineup for some gym leaders (such as Byron.), there might be the possibility that Cynthia might not own a Togekiss in the Anime (heck, for all we know, two thirds of her team might not even be the same as the Team she has in Diamond, Pearl, or Platinum.). The only sensible way for Togekiss to appear aside from Cynthia's team (assuming that it's even going to follow her Platinum team) is through Misty's Togetic making a reappearance. Since Bulbapedia, and by proxy, the fanbase as a whole, doesn't count movie appearances as actual debuts in the anime (otherwise, I think Mantyke would have been listed as having debuted in Temple of the Sea instead of at "One Team, Two Team, Red Team, Blue Team"), Togekiss's cameo in the Shaymin movie isn't likely to be counted, anyways.