Ideally, I would have preferred if a new Supergirl film were made first
I read from time to time about Supergirl being rumored to appear in Man of Steel 2 but that film seems to be at least 2 or 3 years away if it ever happens. Would be good to see Superman and Supergirl together on the big screen though.
Romulus, did you ever read the story (attached) of Ilya Salkind's idea to have Supergirl in Superman 3?.
As with anything, take what you read with a grain of salt until it is actually greenlit and in production.
Certainly am in regards to this news, Joss was going to do a Wonder Woman movie back in the Mid 2000's but that ended up coming to nothing. I hope this Batgirl movie does go ahead.
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I'm glad Supergirl didn't appear in Superman III since it was a very comedic film. The SM franchise back in the 1980s went downhill after Donner was fired / let go and the films (particularly III and IV) became parodies / overly-earnest caricatures of themselves and almost unwatchable. The original Supergirl film back in 1984 was a product of that era's wonky thinking. Good idea, but poor execution and a lousy outcome. The character's introduction was ideal, but the timing and social attitudes were completely off.
As for the prospects of a Batgirl film, lets first see how Wonder Woman and Captain Marvel fare in the next few years before making any predictions or judgements if / when such a film is made.
Personally, I'd prefer not to see Supergirl appear in Man of Steel 2. If Zach Snyder is / will be helming it, then it would damage the essence of who Supergirl is / is supposed to be. Yet, a stand-alone non-ZS film would be fine, provided whomever helmed it actually took the time to research, properly develop, and knew how to treat the character respectfully. Technically, ZS is fine, but from an artistic interpretive take, his recent superhero works are hard to accept.
If the anticipated MoS 2 has Supergirl in it and it is in the same vein as MoS or the Justice League films, it might be more detrimental to the character's overall public acceptance and may hamper any future SG feature film projects. I could be mistaken and it could turn out to be considered a rousing success (by Hollywood's money-making standards), but I feel that the current crop of DCU feature films are somehow missing the mark.
"God Bless The Infidels" - The Sadies, CD/LP/Download album Northern Passages (2017)