Last week, actress Teresa Palmer (Lights Out, Hacksaw Ridge) revealed during an interview that she is interested in joining the DCEU. The actress said that she'd love to bring Talia al Ghul to life in the upcoming Batman flicks.
Previously, the character appeared in Christopher Nolan's The Dark Knight Rises, portrayed by Marion Cotillard. Since Deathstroke was confirmed to appear in both the Justice League and the first solo Batman flick of the DCEU, it would make sense for Talia al Ghul to appear, as well (since a connection could be made, with Deathstroke being an assassin while Talia is the daughter of the leader of the League of Assassins).
However, according to The Wrap, there are no plans for Talia al Ghul to join the DCEU anytime soon. The same is said about her father, Ra's al Ghul:
Our insider says that neither Talia al Ghul nor her dad will be in The Batman "” or any DC film on the horizon. (via Screen Rant)
Would it have been better if Talia were announced for future DCEU movies? Yes, especially since this shared universe lacks any strong female presence (except for, of course, Gal Gadot's Wonder Woman). If we also take into account that we have yet to see a remarkable villainess on the big screen (except for Catwoman, of course, but she was hardly a straight-up villain in either the Nolan or the Tim Burton movie), the addition of Talia al Ghul would have been more than welcome.
However, even if this character were announced, is Teresa Palmer a good choice to play her? According to some, she isn't - especially since the character is described as being of Arabic and Chinese descent.
Anyway, the Batman film is, reportedly, going to include quite a few villains from Batman's rogues gallery. And once Wonder Woman is released and we hear something certain about the Harley Quinn spin-off, the DCEU will have plenty of female characters.